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Timestamp: 2015-10-10 18:36:12
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Patent US7812766 - Locating a mobile station and applications therefor - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsA location system is disclosed for wireless telecommunication infrastructures. The system is an end-to-end solution having one or more location systems for outputting requested locations of hand sets or mobile stations (MS) based on, e.g., AMPS, NAMPS, CDMA or TDMA communication standards, for processing...http://www.google.com/patents/US7812766?utm_source=gb-gplus-sharePatent US7812766 - Locating a mobile station and applications thereforAdvanced Patent SearchPublication numberUS7812766 B2Publication typeGrantApplication numberUS 11/069,441Publication dateOct 12, 2010Filing dateMar 1, 2005Priority dateSep 9, 1996Fee statusPaidAlso published asUS6236365, US6952181, US8994591, US20030222819, US20060025158, US20110244887Publication number069441, 11069441, US 7812766 B2, US 7812766B2, US-B2-7812766, US7812766 B2, US7812766B2InventorsFrederick W. LeBlanc, Dennis J. Dupray, Charles L. KarrOriginal AssigneeTracbeam LlcExport CitationBiBTeX, EndNote, RefManPatent Citations (323), Non-Patent Citations (90), Referenced by (57), Classifications (46), Legal Events (2) External Links: USPTO, USPTO Assignment, EspacenetLocating a mobile station and applications therefor
US 7812766 B2Abstract
A location system is disclosed for wireless telecommunication infrastructures. The system is an end-to-end solution having one or more location systems for outputting requested locations of hand sets or mobile stations (MS) based on, e.g., AMPS, NAMPS, CDMA or TDMA communication standards, for processing both local mobile station location requests and more global mobile station location requests via, e.g., Internet communication between a distributed network of location systems. The system uses a plurality of mobile station locating technologies including those based on: (1) two-way TOA and TDOA; (2) home base stations and (3) distributed antenna provisioning. Further, the system can be modularly configured for use in location signaling environments ranging from urban, dense urban, suburban, rural, mountain to low traffic or isolated roadways. The system is useful for 911 emergency calls, tracking, routing, people and animal location including applications for confinement to and exclusion from certain areas.
1. A method for navigating a wireless mobile unit and a communication device closer together, wherein there is a network having a plurality of geographically spaced apart stationary network access units for at least one of transmitting and receiving wireless signals with the mobile unit comprising:
(a) receiving a request via a wireless communication with the mobile unit, wherein the request is for at least one of locating and contacting at least one of one or more mobile entities, wherein there is pre-existing information associated in a predetermined data storage with information for a user of the mobile unit, the pre-existing information including for each of the one or more mobile entities, data identifying the mobile entity or identifying a corresponding communication device therefor;
(b) obtaining, from computational machinery, a location for the mobile unit, the location determined using measurements of wireless signals received from one of: the mobile unit and at least one of the network access units;
(c) accessing the pre-existing information from the predetermined data storage for thereby obtaining identification data for an item (ITM), the ITM being one of: the one or more mobile entities, or the corresponding communication device therefor, wherein ITM is to be provided with data related to the location of the mobile unit;
(d) obtaining a location for the corresponding communication device for one of the mobile entities (ME) by issuing a request to the network to locate the corresponding communication device for the mobile entity ME; and
(e) when the one mobile entity ME or the corresponding communication device therefor is also the item ITM, a step of determining at least one navigational direction for moving the user and the mobile entity ME nearer to one another, the step of determining using the location of the mobile unit and the location for the corresponding communication device for ME.
2. The method of claim 1, wherein the received request is for locating one or more persons having contact information accessible from the pre-existing information, said item ITM being one of the persons.
3. The method of claim 1, wherein the location of the one communication device is determined using measurements of wireless signals received from one of: the one communication device and the access points of the network, and further including a step of outputting the at least one navigational direction to the item ITM wirelessly via the network.
4. The method of claim 3, wherein the step of outputting includes transmitting the at least one navigational direction on the Internet.
5. The method of claim 3, wherein the step of outputting includes transmitting the at least one navigational direction via a short message service.
6. The method of claim 1, wherein the receiving step (a) includes receiving the request at an Internet site.
7. The method of claim 1, further including selecting the mobile entity ME as the item ITM for providing thereto the data related to the location of the user thereto, wherein the selection is based on a proximity of the determined mobile entity ME to the mobile unit.
8. The method of claim 7, wherein the item ITM is a person, and said step of selecting includes determining an authorization for the person to obtain the data related to the location of the mobile unit.
9. The method of claim 1, wherein the at least one navigational direction includes a route between the user and the item ITM for bringing the user and the item ITM together.
10. The method of claim 1, further including a step of determining the location for at least one of: the mobile unit and the item ITM by performing a step of adjusting a confidence value for at least one location estimate for at least one of: the mobile unit and the item ITM;
wherein values for at least some of the following factors are used in adjusting the confidence value: (a) how closely the at least one location estimate matches a predetermined road, (b) how likely an estimated velocity for the at least one of: the mobile unit and the item ITM is for a geographical area having the at least one location estimate; (c) how closely the at least one location estimate corresponds to a different estimate for locating the at least one of: the mobile unit and the one item ITM; and (d) how closely the at least one location estimate corresponds to an extrapolated location estimate of the at least one of: the mobile unit and the item ITM.
11. The method of claim 1, wherein the one communication device for ME is a wireless mobile unit, and said step (d) of obtaining includes requesting a wireless location of the corresponding communication device for the mobile entity ME.
12. The method of claim 1, further including establishing a call between the user and the item ITM.
13. The method of claim 1, further including establishing a conference call related to the request of step (a) between the user and a plurality of other persons, the other persons identified by the mobile entities identified by the pre-existing information.
14. The method of claim 1, wherein the item ITM is a person, and further including a step of authorizing the person to receive the at least one navigational direction.
15. The method of claim 1, wherein the location of the corresponding communication device, for the mobile entity ME, is obtained using measurements of wireless signals received from the corresponding communication device for the mobile entity ME via the network access units.
16. The method of claim 1, wherein the item ITM is a person, and the person receives the at least one navigational direction audibly.
17. The method of claim 1, wherein the item ITM is a person, and by following the at least one navigational direction, the person arrives at a location of the user.
18. A method for providing a navigational service between multiple mobile devices, and one or more networks of wireless stationary access units for communicating with the mobile devices, comprising:
storing information related to users for the navigational service;
communicating with the networks, wherein the navigational service is configured to:
(a) receive a command via one of the access units, wherein the command is from one of the mobile devices of one of the users, the command for at least one of contacting or locating at least one mobile entity able to communicate with the access points via a corresponding one of the mobile devices for the mobile entity, wherein there is pre-existing data associated in a predetermined data storage with the user of the one mobile device for identifying one or more mobile entities, including the at least one mobile entity;
(b) provide a request to a location determining service for determining a location of one of the mobile entities or corresponding mobile devices therefor, wherein the one mobile entity is identified as being authorized to be provided with data (D) related to a location of the user, the data D determined by the location determining service in responding to the request;
(c) request a location of the one mobile device; and
(d) request at least one navigational direction for moving the one user and the one mobile entity nearer to one another using a result from the step (b), and a result from the step (c).
19. The method of claim 18, wherein outputting the at least one navigational direction to the at least one mobile entity which is a person.
20. The method of claim 18, wherein each of the at least one mobile entity is a person, or includes a wireless mobile station.
21. The method of claim 18, wherein the location determining service includes a plurality of Internet accessible sites distributed on the Internet so that various location estimates are determined by the location service at geographically spaced apart ones of the plurality of Internet sites.
22. The method of claim 18, further including a step of determining that the one mobile entity is nearer for reaching the one user than another of the mobile entities.
23. The method of claim 18, further including a step of activating a conference call between the one mobile entity, the one user, and another of the mobile entities.
24. The method of claim 18, further including initiating a process for providing the one mobile entity with the at least one navigational direction, wherein the at least one navigational direction includes directions from a location for the one mobile entity to a location of the one user.
25. An apparatus for navigating a wireless mobile unit and a mobile communication device closer together, comprising:
a network service accessible via a network having a plurality of geographically spaced apart stationary network access units for at least one of transmitting and receiving wireless signals with the mobile unit;
a predetermined data storage accessible by the network service, the data storage for storing information associated with a user of the mobile unit, the information including for each of one or more entities, corresponding data for identifying the entity or for identifying a corresponding mobile communication device therefor, the corresponding mobile communication device for performing wireless communications;
wherein the network service is configured to:
(a) receive a request via a wireless communication between the mobile unit and the network, wherein the request is for at least one of contacting and locating one of the entities;
(b) obtain a location for the mobile unit, the location determined using a wireless location process for locating the mobile unit wirelessly, the process performed by computational machinery;
(c) determine, using the information of the data storage, an item (ITM), the ITM being one of: the one or more entities, or the corresponding communication device therefor, wherein ITM is to be provided with data related to the location of the mobile unit;
(d) obtain a location for the corresponding communication device for one of the entities (ME) by issuing a request to locate the corresponding communication device for the one entity ME; and
(e) when the one entity ME or the corresponding communication device therefor is also the item ITM, determine at least one navigational direction for moving the user and the one entity ME nearer to one another, wherein the at least one navigational direction is determined using the location of the mobile unit and the location for the corresponding communication device for the one entity ME.
26. The apparatus of claim 25, wherein the communication device for the one entity ME includes a wireless mobile station, wherein the location of (d) is determined by computational machinery that performs a wireless location process that locates the wireless mobile station wirelessly.
27. The apparatus of claim 26, wherein the information of the predetermined data storage includes data for selectively identifying the one entity ME as being allowed to receive data related to the user.
28. The apparatus of claim 26, wherein the network service initiates a process, performed by computational machinery, for providing the one entity ME with the at least one navigational direction, wherein the at least one navigational direction includes directions from a location for the one entity ME to a location of the user.
29. The apparatus of claim 26, wherein the network service determines that the one entity ME is nearer for reaching the user than another of the entities.
30. The apparatus of claim 26, wherein the network service activates a conference call between the one entity ME, the one user, and another of the entities.
a continuation of U.S. application Ser. No. 09/820,584 filed Mar. 28, 2001, and a continuation-in-part of U.S. application Ser. No. 09/194,367 filed Nov. 24, 1998; U.S. application Ser. No. 09/820,584 is a continuation of U.S. application Ser. No. 09/230,109 filed Jul. 8, 1999 (now U.S. Pat. No. 6,236,365) which is the National Stage of International Application No. PCT/US97/15933 filed Sep. 8, 1997 which, in turn, claims the benefit of the following three applications: U.S. Provisional Application No. 60/056,603 filed Aug. 20, 1997, U.S. Provisional Application No. 60/044,821 filed Apr. 25, 1997; and U.S. Provisional Application No. 60/025,855 filed Sep. 9, 1996; U.S. application Ser. No. 09/194,367 is the National Stage of International Application No. PCT/US97/15892, filed Sep. 8, 1997, which claims the benefit of the following three provisionals: U.S. Provisional Application No. 60/056,590 filed Aug. 20, 1997; U.S. Provisional Application No. 60/044,821 filed Apr. 25, 1997; and U.S. Provisional Application No. 60/025,855 filed Sep. 9, 1996. All the above cited references are fully incorporated by reference herein. RELATED FIELD OF THE INVENTION
The present invention is directed generally to a system and method for locating people or objects, and in particular to a system and method for locating a wireless mobile radio station in a macro base station, distributed antenna, or home base station environment.
Wireless communications systems are becoming increasingly important worldwide. Wireless cellular telecommunications systems are rapidly replacing conventional wire-based telecommunications systems in many applications. Commercial mobile radio service provider networks, and specialized mobile radio and mobile data radio networks are examples. The general principles of wireless cellular telephony have been described variously, for example in U.S. Pat. No. 5,295,180 to Vendetti, et al filed Apr. 8, 1992, which is incorporated herein by reference. There is great interest in using existing infrastructures for wireless communication systems for locating people and/or objects in a cost-effective manner. Such a capability would be invaluable in a variety of situations, especially in emergency or crime situations. Due to the substantial benefits of such a location system, several attempts have been made to design and implement such a system. Systems have been proposed that rely upon signal strength and trilateralization techniques to permit location include those disclosed in U.S. Pat. No. 4,818,998 filed Mar. 31, 1986 and U.S. Pat. No. 4,908,629 filed Dec. 5, 1988 both to Apsell et al. (“the Apsell patents”), and U.S. Pat. No. 4,891,650 to Sheffer (“the Sheffer patent”) filed May 16, 1988. The Apsell patents disclose a system employing a “homing-in” scheme using radio signal strength, wherein the scheme detects radio signal strength transmitted from an unknown location. This signal strength is detected by nearby tracking vehicles, such as police cruisers using receivers with directional antennas. Alternatively, the Sheffer patent discloses a system using the FM analog cellular network. This system includes a mobile transmitter located on a vehicle to be located. The transmitter transmits an alarm signal upon activation to detectors located at base stations of the cellular network. These detectors receive the transmitted signal and transmit, to a central station, data indicating the signal strength of the received signal and the identity of the base stations receiving the signal. This data is processed to determine the distance between the vehicle and each of the base stations and, through trilateralization, the vehicle's position. However, these systems have drawbacks that include high expense in that special purpose electronics are required. Furthermore, the systems are generally only effective in line-of-sight conditions, such as rural settings. Radio wave surface reflections, refractions and ground clutter cause significant distortion, in determining the location of a signal source in most geographical areas that are more than sparsely populated. Moreover, these drawbacks are particularly exacerbated in dense urban canyon (city) areas, where errors and/or conflicts in location measurements can result in substantial inaccuracies.
Another example of a location system using time of arrival and triangulation for location are satellite-based systems, such as the military and commercial versions of the Global Positioning Satellite system (GPS). GPS can provide accurate position determination (i.e., about 100 meters error for the commercial version of GPS) from a time-based signal received simultaneously from at least three satellites. A ground-based GPS receiver at or near the object to be located determines the difference between the time at which each satellite transmits a time signal and the time at which the signal is received and, based on the time differentials, determines the object's location. However, the GPS is impractical in many applications. The signal power levels from the satellites are low and the GPS receiver requires a clear, line-of-sight path to at least three satellites above a horizon of about 60 degrees for effective operation. Accordingly, inclement weather conditions, such as clouds, terrain features, such as hills and trees, and buildings restrict the ability of the GPS receiver to determine its position. Furthermore, the initial GPS signal detection process for a GPS receiver is relatively long (i.e., several minutes) for determining the receivers position. Such delays are unacceptable in many applications such as, for example, emergency response and vehicle tracking.
Additionally, GPS-based location systems have been attempted in which the received GPS signals are transmitted to a central data center for performing location calculations. Such systems have also met with limited success due, for example, to the limited reception of the satellite signals and the added expense and complexity of the electronics required for an inexpensive location mobile station or handset for detecting and receiving the GPS signals from the satellites.
The behavior of a mobile radio signal in the general environment is unique and complicated. Efforts to perform correlation between radio signals and distance between a base station and a mobile station are similarly complex. Repeated attempts to solve this problem in the past have been met with only marginal success. Factors include terrain undulations, fixed and variable clutter, atmospheric conditions, internal radio characteristics of cellular and PCS systems, such as frequencies, antenna configurations, modulation schemes, diversity methods, and the physical geometry of direct, refracted and reflected waves between the base stations and the mobile. Noise, such as man-made externally sources (e.g., auto ignitions) and radio system co-channel and adjacent channel interference also affect radio reception and related performance measurements, such as the analog carrier-to-interference ratio (C/I), or digital energy-per-bit/Noise density ratio (Eb/No) and are particular to various points in time and space domains.
Before discussing real world correlation between signals and distance, it is useful to review the theoretical premise, that of radio energy path loss across a pure isotropic vacuum propagation channel, and its dependencies within and among various communications channel types.
One consequence from a location perspective is that the effective range of values for higher exponents is an increased at higher frequencies, thus providing improved granularity of ranging correlation.
Actual data collected in real-world environments uncovered huge variations with respect to the free space path loss equation, giving rise to the creation of many empirical formulas for radio signal coverage prediction. Clutter, either fixed or stationary in geometric relation to the propagation of the radio signals, causes a shadow effect of blocking that perturbs the free space loss effect. Perhaps the best known model set that characterizes the average path loss is Hata's, “Empirical Formula for Propagation Loss in Land Mobile Radio”, M. Hata, IEEE Transactions VT-29, pp. 317-325, August 1980, three pathloss models, based on Okumura's measurements in and around Tokyo, “Field Strength and its Variability in VHF and UHF Land Mobile Service”, Y. Okumura, et al, Review of the Electrical Communications laboratory, Vol 16, pp 825-873, September-October 1968.
Although the Hata model was found to be useful for generalized RF wave prediction in frequencies under 1 GHz in certain suburban and rural settings, as either the frequency and/or clutter increased, predictability decreased. In current practice, however, field technicians often have to make a guess for dense urban an suburban areas (applying whatever model seems best), then installing a base stations and begin taking manual measurements.
In 1991, U.S. Pat. No. 5,055,851 to Sheffer filed Nov. 29, 1989 taught that if three or more relationships have been established in a triangular space of three or more base stations (BSs) with a location database constructed having data related to possible mobile station (MS) locations, then arculation calculations may be performed, which use three distinct Por measurements to determine an X,Y, two dimensional location, which can then be projected onto an area map. The triangulation calculation is based on the fact that the approximate distance of the mobile station (MS) from any base station (BS) cell can be calculated based on the received signal strength. Sheffer acknowledges that terrain variations affect accuracy, although as noted above, Sheffer's disclosure does not account for a sufficient number of variables, such as fixed and variable location shadow fading, which are typical in dense urban areas with moving traffic.
Most field research before about 1988 has focused on characterizing (with the objective of RF coverage prediction) the RF propagation channel (i.e., electromagnetic radio waves) using a single-ray model, although standard fit errors in regressions proved dismal (e.g., 40-80 dB). Later, multi-ray models were proposed, and much later, certain behaviors were studied with radio and digital channels. In 1981, Vogler proposed that radio waves at higher frequencies could be modeled using optics principles. In 1988 Walfisch and Bertoni applied optical methods to develop a two-ray model, which when compared to certain highly specific, controlled field data, provided extremely good regression fit standard errors of within 1.2 dB.
In the Bertoni two ray model it was assumed that most cities would consist of a core of high-rise buildings surrounded by a much larger area having buildings of uniform height spread over regions comprising many square blocks, with street grids organizing buildings into rows that are nearly parallel. Rays penetrating buildings then emanating outside a building were neglected.
After a lengthy analysis it was concluded that path loss was a function of three factors: 1.) the path loss between antennas in free space; 2.) the reduction of rooftop wave fields due to settling; and 3.) the effect of diffraction of the rooftop fields down to ground level.
However, a substantial difficulty with the two-ray model in practice is that it requires a substantial amount of data regarding building dimensions, geometry, street widths, antenna gain characteristics for every possible ray path, etc. Additionally, it requires an inordinate amount of computational resources and such a model is not easily updated or maintained.
Unfortunately, in practice clutter geometry and building heights are random. Moreover, data of sufficient detail is extremely difficult to acquire, and regression standard fit errors are poor; i.e., in the general case, these errors were found to be 40-60 dB. Thus the two-ray model approach, although sometimes providing an improvement over single ray techniques, still did not predict RF signal characteristics in the general case to level of accuracy desired (<10 dB).
Work by Greenstein has since developed from the perspective of measurement-based regression models, as opposed to the previous approach of predicting-first, then performing measurement comparisons. Apparently yielding to the fact that low-power, low antenna (e.g., 12-25 feet above ground) height PCS microcell coverage was insufficient in urban buildings, Greenstein, et al, authored “Performance Evaluations for Urban Line-of-sight Microcells Using a Multi-ray Propagation Model”, in IEEE Globecom Proceedings, December 1991. This paper proposed the idea of formulating regressions based on field measurements using small PCS microcells in a lineal microcell geometry (i.e., geometries in which there is always a line-of-sight path between a subscriber's mobile and its current microsite). Additionally, Greenstein studied the communication channels variable Bit-Error-Rate (BER) in a spatial domain, which was a departure from previous research that limited field measurements to the RF propagation channel signal strength alone. However, Greenstein based his finding on two suspicious assumptions: 1) he assumed that distance correlation estimates were identical for uplink and downlink transmission paths; and 2) modulation techniques would be transparent in terms of improved distance correlation conclusions. Although some data held very correlation, other data and environments produced poor results. Accordingly, his results appear unreliable for use in general location context.
In 1993 Greenstein, et al, authored “A Measurement-Based Model for Predicting Coverage Areas of Urban Microcells”, in the IEEE Journal On Selected Areas in Communications, Vol. 11, No. 7, September 1993. Greenstein reported a generic measurement-based model of RF attenuation in terms of constant-value contours surrounding a given low-power, low antenna microcell environment in a dense, rectilinear neighborhood, such as New York City. However, these contours were for the cellular frequency band. In this case, LOS and non-LOS clutter were considered for a given microcell site. A result of this analysis was that RF propagation losses (or attenuation), when cell antenna heights were relatively low, provided attenuation contours resembling a spline plane curve depicted as an asteroid, aligned with major street grid patterns. Further, Greenstein found that convex diamond-shaped RF propagation loss contours were a common occurrence in field measurements in a rectilinear urban area. The special plane curve asteroid is represented by the formula:
x2/3+y2/3=r2/3. However, these results alone have not been sufficiently robust and general to accurately locate an mobile station, due to the variable nature of urban clutter spatial arrangements.
At Telesis Technology in 1994 Howard Xia, et al, authored “Microcellular Propagation Characteristics for Personal Communications in Urban and Suburban Environments”, in IEEE Transactions of Vehicular Technology, Vol. 43, No. 3, August 1994, which performed measurements specifically in the PCS 1.8 to 1.9 GHz frequency band. Xia found corresponding but more variable outcome results in San Francisco, Oakland (urban) and the Sunset and Mission Districts (suburban).
The physical radio propagation channel perturbs signal strength, frequency (causing rate changes, phase delay, signal to noise ratios (e.g., C/I for the analog case, or Eb/No, RF energy per bit, over average noise density ratio for the digital case) and Doppler-shift. Signal strength is usually characterized by:
Free Space Path Loss (Lp)
Slow fading loss or margin (Lslow)
Fast fading loss or margin (Lfast)
The cell designer increases the transmitted power PTX by the shadow fading margin Lslow which is usually chosen to be within the 1-2 percentile of the slow fading probability density function (PDF) to minimize the probability of unsatisfactorily low received power level PRX at the receiver. The PRX level must have enough signal to noise energy level (e.g., 10 dB) to overcome the receiver's internal noise level (e.g., −118 dBm in the case of cellular 0.9 GHz), for a minimum voice quality standard. Thus in this example PRX must never be below −108 dBm, in order to maintain the quality standard.
Additionally the short term fast signal fading due to multipath propagation is taken into account by deploying fast fading margin Lfast, which is typically also chosen to be a few percentiles of the fast fading distribution. The 1 to 2 percentiles compliment other network blockage guidelines. For example the cell base station traffic loading capacity and network transport facilities are usually designed for a 1-2 percentile blockage factor as well. However, in the worst-case scenario both fading margins are simultaneously exceeded, thus causing a fading margin overload.
In Roy Steele's, text, Mobile Radio Communications, IEEE Press, 1992, estimates for a GSM system operating in the 1.8 GHz band with a transmitter antenna height of 6.4 m and a mobile station receiver antenna height of 2 m, and assumptions regarding total path loss, transmitter power would be calculated as follows:
GSM Power Budget Example
dBm value
Lslow 14
Lfast 7
LIpath 110
Min. RX pwr required
TXpwr = 27 dBm
Steele's sample size in a specific urban London area of 80,000 LOS measurements and data reduction found a slow fading variance of
σ=7 dB
assuming log-normal slow fading PDF and allowing for a 1.4% slow fading margin overload, thus
L slow=2σ=14 dB
The fast fading margin was determined to be:
Lfast=7 dB
In contrast, Xia's measurements in urban and suburban California at 1.8 GHz uncovered flat-land shadow fades on the order of 25-30 dB when the mobile station (MS) receiver was traveling from LOS to non-LOS geometries. In hilly terrain fades of +5 to −50 dB were experienced. Thus it is evident that attempts to correlate signal strength with mobile station ranging distance suggest that error ranges could not be expected to improve below 14 dB, with a high side of 25 to 50 dB. Based on 20 to 40 dB per decade, Corresponding error ranges for the distance variable would then be on the order of 900 feet to several thousand feet, depending upon the particular environmental topology and the transmitter and receiver geometries.
Although the acceptance of fuzzy logic has been generally more rapid in non-American countries, the principles of fuzzy logic can be applied in wireless location. Lotfi A. Zadeh's article, “Fuzzy Sets” published in 1965 in Information and Control, vol. 8, Pg 338-353, herein incorporated by reference, established the basic principles of fuzzy logic, among which a key theorem, the FAT theorem, suggests that a fuzzy system with a finite set of rules can uniformly approximate any continuous (or Borel-measureable) system. The system has a graph or curve in the space of all combinations of system inputs and outputs. Each fuzzy rule defines a patch in this space. The more uncertain the rule, the wider the patch. A finite number of small patches can always cover the curve. The fuzzy system averages patches that overlap. The Fat theorem was proven by Bart Kosko, in a paper entitled, “Fuzzy Systems as Universal Approximators”, in Proceedings of the First IEEE Conference on Fuzzy Systems, Pages 1153-1162, in San Diego, on March, 1992, herein incorporated by reference.
Fuzzy relations map elements of one universe, say “X”, to those of another universe, say “Y”, through the Cartesian product of the two universes. However, the “strength” of the relation between ordered pairs of the two universes is not measured with the characteristic function (in which an element is either definitely related to another element as indicated by a strength value of “1”, or is definitely not related to another element as indicated by a strength value of “0”, but rather with a membership function expressing various “degrees” of strength of the relation on the unit interval [0,1]. Hence, a fuzzy relation R is a mapping from the Cartesian space X�Y to the interval [0,1], where the strength of the mapping is expressed by the membership function of the relation for ordered pairs from the two universes or μR(x,y).
Just as for crisp relations, the properties of commutativity, associativity, distributivity, involution and idempotency all hold for fuzzy relations. Moreover, DeMorgan's laws hold for fuzzy relations just as they do for crisp (classical) relations, and the null relations O, and the complete relation, E, are analogous to the null set and the whole set in set-theoretic from, respectively. The properties that do not hold for fuzzy relations, as is the case for fuzzy sets in general, are the excluded middle laws. Since a fuzzy relation R is also a fuzzy set, there is overlap between a relation and its complement, hence.
R∪R′≠E
R∩R′≠O
As seen in the foregoing expression, the excluded middle laws for relation do not result in the null relation, O, or the complete relation, E. Because fuzzy relations in general are fuzzy sets, the Cartesian product can be defined as a relations between two or more fuzzy sets. Let A be a fuzzy set on universe X and B be a fuzzy set on universe Y; then the Cartesian product between fuzzy sets A and B will result in a fuzzy relation R, which is contained within the full Cartesian product space, or
A�B=R⊂X�Y
where the fuzzy relation R has membership function:
μR(x,y)=μA�B(x,y)=min(μA(x),μB(y))
Fuzzy composition can be defined just as it is for crisp (binary) relations. If R is a fuzzy relation on the Cartesian space X�Y, and S is a fuzzy relation on the Cartesian space Y�Z, and T is a fuzzy relation on the Cartesian space X�Z; then fuzzy max-min composition is defined in terms of the set-theoretic notation and membership function-theoretic notation in the following manner:
μT(x,y)= (μR(x,y) μS(x,y))=max { min [μR(x,y),μS(y,z)]}
The fuzzy extension principle allows for transforms or mappings of fuzzy concepts in the form y=f(x). This principle, combined with a compositional rule of inference, allows for a crisp input to be mapped through a fuzzy transform using membership functions into a crisp output. Additionally, in mapping a variable x into a variable y, both x and y can be vector quantities.
It is an objective of the present invention to provide a system and method for determining wireless location using one or more commercial mobile radio telecommunication systems for accurately locating people and/or objects in a cost effective manner. Related objectives for the present invention include providing a system and method that:
(1) can be readily incorporated into existing commercial wireless telephony systems with few, if any, modifications of a typical telephony wireless infrastructure; (2) can use the native electronics of typical commercially available telephony wireless mobile stations (e.g., handsets) as location devices; (3) can be used for locating people and/or objects residing indoors. Yet another objective is to provide a low cost location system and method, adaptable to wireless telephony systems, for using simultaneously a plurality of base stations owned and/or operated by competing commercial mobile radio service providers within a common radio coverage area, in order to achieve FCC phase 2 or other accuracy requirements, and for synergistically increasing mobile station location accuracy and consistency.
Yet another objective is to provide a low cost location system and method, adaptable to wireless telephony systems, for using a plurality of location techniques In particular, at least some of the following mobile station location techniques can be utilized by various embodiments of the present invention:
(4.1) time-of-arrival wireless signal processing techniques;
(4.2) time-difference-of-arrival wireless signal processing techniques;
(4.3) adaptive wireless signal processing techniques having, for example, learning capabilities and including, for instance, neural net and genetic algorithm processing;
(4.4) signal processing techniques for matching MS location signals with wireless signal characteristics of known areas;
(4.5) conflict resolution techniques for resolving conflicts in hypotheses for MS location estimates;
(4.6) enhancement of MS location estimates through the use of both heuristics and historical data associating MS wireless signal characteristics with known locations and/or environmental conditions.
Yet another objective is to provide a system and method for flexible delivery of location information to Public Safety Answering Points, end users, centralized dispatchers, as well as to agents (either human or mechanized) associated with trigger-based inventory and tracking systems. Flexible delivery used here indicates providing location via various two dimensional closed-form shapes, such as polygons, ellipses, etc., which bound the location probabilities. In cases where height location information is known, the bounding shape may be three-dimensional.
Yet another objective is to provide a system and method for a variety of new location-based services for public and private group safety, including family support functions.
Yet another objective is to provide a system and method for National Scale Wireless Location capability. Although the primary focus of this patent is to provide wireless location with accuracy to meet the FCC phase two requirements, a system and method is provided that also utilizes roaming signaling to determine in which city is a particular wireless mobile station located.
Yet another objective is to provide and system and method for Parametric-driven, intelligent agent-based location services. Parameters may include time, location, and user-specific and/or group specific criteria.
Yet another objective is to provide a system and method for determining and/or enhancing wireless location using one or more of the following: (a.) CDMA-based Distributed Antenna technology; (b.) Home Base Stations and AIN technology.
Yet another objective is to provide notification messages and/or voice-synthesized call or text paging function to a plurality of other mobile station users when a mobile station user travels into, or away from, one or more zones or are within short distances of shopping malls, stores, merchandising dealers etc.
Yet another objective is to provide notification messages and/or voice-synthesized call or text paging functions to a plurality of other mobile station users when a mobile station dials a redefined telephone number, such as 911, or a type of “mild emergency cry for help” number.
Yet another objective is to provide notification messages and/or voice-synthesized call or text paging function to a plurality of other mobile station users when a mobile station user dials a predefined telephone number, such as 311, or a type of mild emergency cry for help number, wherein the plurality of other mobile station users are within a particular distance, or a minimum distance to the mobile station user who dialed the predefined number.
Yet another objective is to provide notification messages and/or voice-synthesized call or text paging function to a plurality of other mobile station users when a mobile station user dials a predefined telephone number, such as 311, or a type of mild emergency cry for help number, wherein the plurality of other mobile station users are within a particular distance, or a minimum distance to the mobile station user who dialed the predefined number, and wherein the other mobile station users are provided individualized directional or navigation information from their current locations, to reach to the mobile station user who dialed the predefined number.
Yet another objective is to provide automatic home office, vehicle and boat security functions, which are activated and deactivated based on a mobile station user's location to or away from a location associated with the security functions.
Yet another objective is to provide notifications (e.g., via fax, page, e-mail, text paging or voice synthesized call message), or to setup a group conference call capability to a plurality of predefined individuals, based on a mobile station user's call to 911, or based on a mobile station user's traveling into or away from a location zone or area, or based upon a sensor input signal to the user's mobile station, such as a sudden change in G forces, such as falling down, having the car hit another object suddenly, air bag deployment, etc.
Yet another objective is to provide location information to a ‘searcher’ mobile station user who then further refines or narrows the scope of the location/search for a ‘target’ mobile station, or the mobile station to be located, using a small microwave dish, in communication with, or to supplement/replace the searcher mobile station antenna, whose physical orientation is used to further determine the target mobile station location, relative to the searcher's mobile station position/orientation.
Yet another objective is to provide a means to allow more flexible storage, inventory and enhanced user accessibility of rental vehicles, by combining location technology of rental car driver carrying his/her own mobile station, along with a mobile station which remains always active and fixed to a rental car. By maintaining accurate location records of rental car locations and automatic, remote-control of rental cars (or smart cars) which use the mobile station to telemeter control data to and from the car, whose doors, door locks, and general accessibility are controlled by a centralized computer system, rental cars can be dropped off at convenient shopping center malls, airport parking lots, hotels and at other convenient locations.
Yet another objective is to provide location estimates to users carrying mobile stations, via voice synthesis, data circuit messaging or text paging.
Yet another objective is to provide a mechanism whereby mobile station users may access and control their subscriber profile for location purposes. The location subscriber profile is a persistent data store which contains logic regarding under what criteria will that mobile station user allow his/her location to be made known, and to whom. The mobile station user may access the location profile via several methods, including Internet means, and mobile station handset keypad entry and voice recognition circuits.
Yet another objective is to utilize signaling detection characteristics of other CDMA base stations and systems in a given area, owned and operated by an another commercial mobile radio service provider (CMRS provider). By including other CMRS providers' infrastructure in the location estimation analysis process, improvements in location accuracy can be realized.
(1) The term wireless herein is, in general, an abbreviation for digital wireless, and in particular, wireless refers to digital radio signaling using one of standard digital protocols such as CDMA, TDMA and GSM, as one skilled in the art will understand. (2) As used herein, the term mobile station (equivalently, MS) refers to a wireless device that is at least a transmitting device, and in most cases is also a wireless receiving device, such as a portable radio telephony handset. Note that in some contexts herein instead or in addition to mobile station, the following terms are also used: personal station (PS), and location unit (LU). In general, these terms may be considered synonymous. However, the later two terms may be used when referring to reduced functionality communication devices in comparison to a typical digital wireless mobile telephone. (3) The term, infrastructure, denotes the network of telephony communication services, and more particularly, that portion of such a network that receives and processes wireless communications with wireless mobile stations. In particular, this infrastructure includes telephony wireless base stations (BS) such as those for radio mobile communication systems based on CDMA, TDMA, and GSM wherein the base stations provide a network of cooperative communication channels with an air interface with the mobile station, and a conventional telecommunications interface with a Mobile Switch Center (MSC). Thus, an MS user within an area serviced by the base stations may be provided with wireless communication throughout the area by user transparent communication transfers (i.e., hand-offs) between the user's mobile station and these base stations in order to maintain effective telephony service. The mobile switch center provides communications and control connectivity among base stations and the public telephone network. (4) An example of a Parametric-driven intelligent agent-based location service follows: An intelligent agent software process monitors sets of Parametric conditions and location scenarios. When appropriate conditions and location criteria are satisfied, then a set of notifications or other actions are triggered to occur. A specific example follows: given that a certain child carrying a mobile station should be in a certain school between 8:00 A.M. and 3:00 P.M. on regular school days, then a wireless location request is invoked periodically, within the school day time frame. If a location request determines that the child's mobile station is located substantially outside of the general school area, then a parent/guardian is notified of that fact, and of the child's location via any of several methods, such as: (a.) a voice-synthesized telephone message, (b.) various extranet/internet means, such as electronic mail, netcasting, such as the product Castanet, by Marimba Software, Inc., (c.) fax to a pre-determined telephone number, or (d.) alpha-numeric text paging. (5) Commercial mobile radio service (CMRS) service provider is the referenced name of the company that owns and/or operates a publicly accessible wireless system in the cellular or PCS spectrum radio bands. (6) The term “geolocation” as used herein refers to “a representation of at least one of: a geographical location or a geographical extent”. Thus, the term “GeoLocation Message” refers to a message that contains a content representative of at least one of: a geographical location or a geographical extent. Moreover, the term “geolocation result” refers to a result that represents at least one of: a geographical location or a geographical extent, and the term “geolocation related processing” is intended to mean “processing that is related to a result that represents at least one of: a geographical location or a geographical extent”. SUMMARY DISCUSSION
The location system of the present invention accomplishes the above and other objectives by the following steps:
(1.) receiving signal data measurements corresponding to wireless communications between a mobile station to be located (herein also denoted the target mobile station) and a wireless telephony infrastructure, wherein the mobile station, MS and/or mobile switch center may be enhanced in certain novel and cost effective ways so as to provide an extended number of values characterizing the wireless signal communications between the target mobile station and the base station infrastructure, such infrastructure including multiple, distinct CMRS where base stations share a common coverage area;
(2.) organizing and processing the signal data measurements received from a given target mobile station and surrounding base stations so that composite wireless signal characteristic values may be obtained from which target mobile station location estimates may be derived. In particular, the signal data measurements are ensembles of samples from the wireless signals received from the target mobile station by the base station infrastructure, and from associated base stations wherein these samples are subsequently filtered using analog and digital spectral filtering.
(3.) providing the resultant location estimation characteristic values to a mobile station location estimate model, wherein each such model (also denoted a “first order model” or FOM) subsequently determines the estimate of the location of the target mobile station based on, for example, the signal processing techniques (1.) through (2.) above.
Accordingly, steps (1.) and (2.) above are performed by a subsystem of the invention denoted the Signal Processing and Filtering Subsystem (or simply the Signal Processing Subsystem). In particular, this subsystem receives samples of wireless signal characteristic measurements such as a plurality of relative signal strengths and corresponding signal time delay value pairs, wherein such samples are used by this subsystem to produce the component with the least amount of multipath, as evidenced in the sample by the short time delay value, wherein each such value pair is associated with wireless signal transmissions between the target mobile station and a particular base station of a predetermined wireless base station infrastructure. Extremely transient signal anomalies such as signal reflection from tree leaves or the passing of a truck are likely to be filtered out by the Signal Processing Subsystem. For example, such an ensemble of data value pairs can be subjected to input cropping and various median filters employing filtering techniques such as convolution, median digital,