U.S. patent application number 12/592447 was filed with the patent office on 2012-09-20 for system and method for location determination for mobile clients.
Invention is credited to Shaowei Pan, Xiaohua Wu, Chuntao Zhang.
Application Number | 20120238293 12/592447 |
Document ID | / |
Family ID | 44062469 |
Filed Date | 2012-09-20 |
United States Patent
Application |
20120238293 |
Kind Code |
A9 |
Pan; Shaowei ; et
al. |
September 20, 2012 |
System and method for location determination for mobile clients
Abstract
A first position (104) of the mobile client is determined at
least in part by utilizing first signals received from at least one
first signal source. The first signal source operates in a first
location determination system (114). A second position (106) of at
least one second signal source (120) is determined by utilizing
both the determined first position of the mobile client and second
signals received from the at least one second signal source (120).
The second signal source (120) operates in a second location
determination system. A third position (116) of the mobile client
is determined utilizing the second signal source (120).
Inventors: |
Pan; Shaowei; (Kildeer,
IL) ; Wu; Xiaohua; (Kildeer, IL) ; Zhang;
Chuntao; (Streamwood, IL) |
Prior
Publication: |
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Document Identifier |
Publication Date |
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US 20110124348 A1 |
May 26, 2011 |
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Family ID: |
44062469 |
Appl. No.: |
12/592447 |
Filed: |
November 25, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11757194 |
Jun 1, 2007 |
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12592447 |
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Current U.S.
Class: |
455/456.2 |
Current CPC
Class: |
G01S 19/10 20130101;
G01S 19/48 20130101 |
Class at
Publication: |
455/456.2 |
International
Class: |
H04W 64/00 20090101
H04W064/00 |
Claims
1. A method of seamlessly determining successive positions of a
mobile client comprising: determining a first position of the
mobile client at least in part by utilizing first signals received
from at least one first signal source, the at least one first
signal source operating in a first location determination system;
determining a second position of at least one second signal source
by utilizing both the determined first position of the mobile
client and second signals received from the at least one second
signal source, the at least one second signal source operating in a
second location determination system; and determining a third
position of the mobile client utilizing the at least one second
signal source.
2. The method of claim 1 wherein the at least one first signal
source and the at least one second signal source are selected from
a group comprising: at least one satellite and at least one
signaling beacon.
3. The method of claim 1 wherein the at least one first signal
source comprises at least one Global Positioning System
(GPS)-compliant satellite and wherein the at least one second
signal source comprises at least one beacon operating in a Wireless
Local Area Network (WLAN).
4. The method of claim 3 wherein the at least one second signal
source comprises an access point (AP) operating in a Wireless Local
Area Network (WLAN).
5. The method of claim 1 further comprising determining a fourth
position of the mobile client by utilizing the third position and
third signals received from at least one third signal source.
6. The method of claim 1 wherein the at least one first signal
source comprises a first Global Positioning System (GPS)-compliant
satellite, a second GPS-compliant satellite, and a third
GPS-compliant satellite, and wherein determining the first position
comprises determining the first position from a triangulation of
the first signals received from the first GPS compliant satellite,
the second GPS-compliant satellite, and the third GPS-compliant
satellite.
7. A mobile client comprising: an interface, the interface adapted
and configured to receive first signals from at least one first
signal source that operates in a first location determination
system and second signals from at least one second signal source
that operates in a second location determination system; and a
controller coupled to the interface and that is adapted and
arranged to determine a first position of a mobile client at least
in part by utilizing the first signals from the at least one first
signal source and that is further adapted and arranged to determine
a second position of at least one second signal source by using
both the first position and the second signals from the at least
one second signal source.
8. The mobile client of claim 7 wherein the at least one first
signal source and the at least one second signal source are
selected from a group comprising: at least one satellite and at
least one signaling beacon.
9. The mobile client of claim 7 wherein the at least one first
signal source comprises at least one Global Positioning System
(GPS)-compliant satellite and wherein the at least one second
signal source comprises at least one beacon operating in a Wireless
Local Area Network (WLAN).
10. The mobile client of claim 7 wherein the controller is further
adapted and arranged to determine a third position of the mobile
client by utilizing the second position and third signals from the
at least one second signal source.
11. The mobile client of claim 7 wherein the at least one signal
source comprises a first Global Positioning System (GPS)-compliant
satellite, a second GPS-compliant satellite, and a third
GPS-compliant satellite, and wherein the controller is programmed
to determine the first position from a triangulation of signals
received from the first GPS-compliant satellite, the second
GPS-compliant satellite; and the third GPS-compliant satellite.
Description
FIELD OF THE INVENTION
[0001] The field of the invention relates generally to networks and
more particularly to locating mobile clients within networks.
BACKGROUND OF THE INVENTION
[0002] In many situations, a mobile client moves between or within
different types of systems and networks. For example, a mobile
client such as a cellular phone, pager, personal digital assistant,
or personal computer may move from a satellite communication system
to a Wireless Local Area network (WLAN). In another example, a
mobile client may move between access points that are positioned
within a WLAN. Today's networks also support services such
ubiquitous computing, context aware services, and the seamless
mobility of mobile clients. In order to provide and support many of
these services, it is often desirable and/or necessary to be able
to track and/or determine the location of the mobile client quickly
and efficiently.
[0003] When a mobile client moves between systems or within
systems, the location of the mobile client may sometimes become
undetermined due to poor or non-existent network coverage or
because of other conditions. For instance, a mobile client may
operate within a satellite system and there may be locations where
coverage from the satellite system is not provided. In another
example, when a mobile client operates within a WLAN that provides
coverage for a building, the mobile client may transition between
different access points within the WLAN, and may be sometimes
unlocatable during these transition periods. Consequently, network
services that depend upon knowing the location of the mobile client
may be difficult or costly to provide.
[0004] Previous systems have attempted to address these situations
and provide for the effective and continuous location determination
of mobile clients. For example, previous WLAN systems have utilized
different types of mapping approaches. In some of these previous
approaches, the mobile client was carried through the building in
order to learn the location of the access points of the WLAN.
Unfortunately, these approaches were expensive, time consuming, and
inconvenient to implement. Additionally, these previous mapping
approaches were often unsuccessful because the location of the
access points was assumed to be known, when, in fact, the location
of the access points was sometimes not known. As a result, these
previous approaches have been unable to allow mobile clients to
seamlessly move between different systems and within different
systems. Additionally, since the location of the mobile client
often became unknown, providing network services that depended upon
knowing the mobile client location became expensive, difficult,
and/or impossible to achieve.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] The above needs are at least partially met through provision
of a system and method for location determination for mobile
clients described in the following detailed description,
particularly when studied in conjunction with the drawings,
wherein:
[0006] FIG. 1 comprises a block diagram of a system for the
location determination of mobile clients in accordance with various
embodiments of the invention;
[0007] FIG. 2 comprises a flow chart of one example of an approach
for determining the location of a mobile client according to
various embodiments of the invention;
[0008] FIG. 3 comprises a block diagram of a system according to
various embodiments of the invention;
[0009] FIG. 4 comprises a flow chart of one approach for
determining the location of a mobile client according to various
embodiments of the invention; and
[0010] FIG. 5 comprises a block diagram of a device according to
various embodiments of the invention.
[0011] Skilled artisans will appreciate that elements in the
figures are illustrated for simplicity and clarity and have not
necessarily been drawn to scale. For example, the dimensions and/or
relative positioning of some of the elements in the figures may be
exaggerated relative to other elements to help to improve
understanding of various embodiments of the present invention.
Also, common but well-understood elements that are useful or
necessary in a commercially feasible embodiment are often not
depicted in order to facilitate a less obstructed view of these
various embodiments of the present invention. It will further be
appreciated that certain actions and/or steps may be described or
depicted in a particular order of occurrence while those skilled in
the art will understand that such specificity with respect to
sequence is not actually required. It will also be understood that
the terms and expressions used herein have the ordinary meaning as
is accorded to such terms and expressions with respect to their
corresponding respective areas of inquiry and study except where
specific meanings have otherwise been set forth herein.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0012] A system and method are provided that substantially
continuously determine the location of a mobile client even as the
mobile client moves between or within different types of networks
or systems. The approaches provided herein provide for the seamless
transitioning of the mobile client between different networks and
within these networks. By knowing the location of the mobile
client, various types of services can be effectively provided to
the mobile client. These approaches are also cost-effective to
implement and do not require a costly and time-consuming mapping
process to be performed.
[0013] In many of these embodiments, a first position of a mobile
client is determined at least in part by utilizing first signals
that are received from at least one first signal source. The first
signal source operates in a first location determination system. A
second position of at least one second signal source is determined
by utilizing both the determined first position of the mobile
client and second signals that are received from at least one
second signal source. The second signal source operates in a second
location determination system. A third position of the mobile
client is then determined utilizing the second signal source. In
other examples, a fourth position of the mobile client is
determined by utilizing a third position of the mobile client and
third signals received from at least one third signal source.
[0014] The first signal source, the second signal source, and the
third signal source may utilize any type of technology. For
example, the first signal source and the second signal source may
be satellite systems or signaling beacons. In one example, the
first signal source includes at least one Global Positioning System
(GPS)-compliant satellite and the second signal source comprises at
least one beacon operating in a Wireless Local Area Network (WLAN).
Furthermore, the beacons may be access points that operate within
the WLAN.
[0015] In others of these approaches, the first signal sources may
include multiple satellites and utilize various techniques to
determine the location of the mobile client. For example, the first
signal sources may include a first GPS-compliant satellite, a
second GPS compliant satellite, and a third GPS-compliant
satellite. In this example, the first position may be determined
from the triangulation of the signals received from the first
GPS-compliant satellite, the second GPS-compliant satellite, and
the third GPS-compliant satellite.
[0016] In others of these approaches, first signals are received
from at least one first signal source at a mobile client. The first
signal source operates in a first location determination system. A
first position of the mobile client is determined using at least in
part the first signals. Second signals are received from at least
one second signal source. The second signal source operates in a
second location determination system. A second position of the
second signal source using at least in part the second signals and
the first position of the mobile client. Reception of the at least
one first signal source is then lost. A third position of the
mobile client is subsequently determined using at least in part the
second position of the at least one second signal source and third
signals received from the second signal source.
[0017] Furthermore, reception of the first signal source may become
partially lost and a fourth position of the mobile client is
subsequently determined using fourth signals received from the
first signal source and fifth signals received from the second
signal source.
[0018] Thus, approaches are provided that substantially
continuously determine the location of a mobile client even as the
mobile client moves between or within networks. The approaches
provided herein allow for the seamless transitioning of the mobile
client between different networks, facilitate the provision of
services to the mobile client, are cost-effective to implement, and
do not require costly and time-consuming mapping processes to be
performed.
[0019] Referring now to FIG. 1, one example of a system for
providing location determination for a mobile client is described.
A mobile client moves into a variety of positions 102, 104, 106,
116, and 118. A satellite system 114 is utilized as a first
location determination system for the mobile client when, for
example, the mobile client is operating outside of any buildings in
an external environment. A WLAN within a given building 124 is
utilized as a second location determination system, for example,
when the mobile client is within or near the building 124. The WLAN
includes a first access point 122 and a second access point 120. It
will be understood that the type and number of location
determination systems may vary. Moreover, it will also be
appreciated that the specific type of location determination
equipment utilized by a particular location determination system
may vary. Furthermore, it will be understood that any of the
systems that provide location determination services may provide
any other type of service or services (e.g., ubiquitous computing,
context aware services, or seamless mobility) to the mobile client.
Additionally, the mobile client may be any type of mobile
communication device such as a cellular phone, pager, personal
digital assistant, or personal computer. Other examples of mobile
clients are possible.
[0020] The satellite system 114 may include multiple satellites and
utilize various techniques to determine the location of the mobile
client. For example, the satellite system 114 may include a first
GPS-compliant satellite, a second GPS-compliant satellite, and a
third GPS compliant satellite. In this example, any of the
positions 102, 104, and 106 of the mobile client may be determined
from a triangulation of the first signals received from the first
GPS-compliant satellite, the second GPS-compliant satellite, and
the third GPS-compliant satellite.
[0021] In one example of the operation of the system of FIG. 1, the
positions 102, 104 and 106 of the mobile client are determined by
utilizing signals received from the satellite system 114. In one
approach, the positions 102, 104, and 106 may be determined by
triangulating signals received from individual satellites employed
by the satellite system 114.
[0022] The position of the access point 120 is then determined by
utilizing both the determined positions 102, 104, and 106 of the
mobile client and signals received from the access point 120. Once
the position of the access point 120 is determined, the position
116 of the mobile client can be determined utilizing the now known
position of the access point 120.
[0023] The mobile client then moves to the position 118 and the
coordinates of the position 118 can be determined by using signals
received from the access point 120. As the mobile client moves
within the building 124, it may sense additional access points
(e.g., the access point 122) having unknown locations. Since the
location of the mobile client is known, the unknown location of the
access point 122 can be determined. In one example, this location
may be obtained by using Received Signal Strength (RSS) techniques.
The location of the mobile client can be determined as it moves
from the location 118 to other locations by using the now known
location of the access point 122. This process can be repeated to
determine the locations of other access points and the positions of
the mobile client as moves into and operates within the coverage
areas of the newly discovered access points.
[0024] In another example of the operation of the system of FIG. 1,
signals from the satellite system 114 are received at the mobile
client. The position 102 and the position 104 of the mobile client
are determined using these signals. At the positions denoted by
reference numerals 102 and 104, signals are received by the mobile
client from the access point 120 in the WLAN. The position of the
access point 120 is then determined using these received signals
and the determined position 102 of the mobile client, for example,
using RSS techniques.
[0025] Reception of the at least one first signal source is then at
least partially lost as the mobile client moves to the position
denoted as 106 and then to the position denoted as 116. In this
case, the position 106 of the mobile client may be determined using
signals received from the satellite system 114 and signals received
from the access point 120. The later position 116 of the mobile
client is subsequently determined using the now known position of
the access point 120 and signals received from the access point
120.
[0026] The location of the access point 120 may be determined using
various techniques. In one example, the position of the access
point 120 may be determined by obtaining three sets of data and
finding the intersection of this data. Specifically, a first set of
data (obtained when the mobile client is at position 102) defines a
first circle 112, a second set of data (obtained when the mobile
client is at position 104) defines a second circle 110 and a third
set of data (obtained when the mobile client is at position 106)
defines a third circle 108. The radius of each circle represents a
distance from the mobile client to the access point 120. From the
perspective of the mobile client, the access point is positioned
somewhere along the radius of each circle 108, 110, or 112.
However, by finding the intersection of the three circles 108, 110,
and 112, the location of the access point can be precisely
determined.
[0027] Referring now to FIG. 2, one example of an approach for
determining the position of a mobile client is described. At step
202, a first location of the mobile client within a first location
determination system is made. For example, a GPS satellite system
may be used to determine the location of the mobile client as the
mobile client operates within the parking lot of a shopping
center.
[0028] At step 206, the position of a second signal source is
determined by using the position determined for the mobile client
(at step 202) and a second location determination system. For
example, the position of an access point may be determined by
knowing the position of the mobile client that was obtained by
using the satellite system (at step 202) and by using RSS
techniques from signals received from the access points.
[0029] At step 208, the mobile client moves. For example, the
mobile client may move from the parking lot into a building. At
step 210, due to the movement, the position of the mobile client
becomes unknown and the position of the mobile client may be
determined by using the known position of the second signal source.
For example, if the second signal source is an access point within
a WLAN, RSS techniques can be used to determine the position of the
mobile client.
[0030] It will be appreciated that the above-described process can
be repeated to determine the position of the mobile client and/or
new signal sources. For example, to continue with the current
example, the known position of the mobile client can be used to
determine unknown positions of other access points in the building.
As the access point locations become known and the position of the
mobile client becomes unknown, the now known positions of the newly
discovered access points can be used to determine the unknown
positions of the mobile client. This "chaining" process can be
repeated as long as needed to seamlessly determine the location of
mobile clients as these mobile clients move between networks or
within networks.
[0031] Referring now to FIG. 3, one example of a system for
determining the location of a mobile client is described. A mobile
client is initially positioned in an exterior location (e.g., a
parking lot) at a first position 302 and moves from the first
position 302 to a second position 304, and then to a third position
306. In any of these locations, the location of the mobile client
is determined by using a GPS satellite system. Additionally, in any
of these positions, the mobile client attempts to locate access
points from an in-building WLAN, and then uses the known position
of the mobile client to determine the positions of these access
points.
[0032] As the mobile client moves from the position 306 to a
location 308, it moves (at least partially) out of the coverage
area of the GPS to a shadow area of a building where reception from
the GPS system may be sporadic and/or unreliable. The mobile client
then moves into a position 310. In the shadow area (positions 308
and 310), both GPS and WLAN systems are available and an aggregate
of both types of data is used to determine the location of the
mobile client.
[0033] The mobile client then moves into an area outside the
coverage of the satellite system (e.g., within the building) to a
position 312 and then to a position 314. The locations of the
mobile client can then be determined using the known positions of
the access points within the building. For example, RSS techniques
can be used to determine the location of the mobile client at
positions 312 and 314.
[0034] It will be appreciated that the mobile client movement
described with respect to the approach of FIG. 3 is one example
only. Moreover, different types of location determination systems
can be used and the positioning of these systems can be altered. In
addition, the movement of the mobile client can be reversed or
changed.
[0035] Furthermore, the process can be used to determine further
mobile client locations. For example, as the mobile client moves
out of the coverage area of known access points in the building, it
can discover new access points and obtain the positions of these
access points by using the known position of the mobile client. The
newly obtained access point locations can in turn be used to
determine the position of the mobile client as it loses
communication (e.g., moves out of the range) of other access
points. In this way, the mobile client can seamlessly transition
between different networks/location determination systems and
within these systems.
[0036] Referring now to FIG. 4, another example of an approach for
determining the location of a mobile client is described. At step
402, the location of a mobile client is recorded and this location
is determined by the GPS system. At step 404, the mobile client
starts to attempt to locate (sniff) for RF beacons (e.g., access
points). At step 406, for all of the listenable RF beacons
determined at step 404, three sets of data are obtained. At step
408, the data is used to obtain the position of the first beacon.
The three sets of data define a circle and the intersection of the
three circles is where the RF beacon is located. At step 410, the
same process is performed to obtain the location of each
beacon.
[0037] At step 412, the mobile client moves into the shadow area of
a building. Under these conditions, the location of the mobile
client is determined by using both the GPS system and the RF
beacons. At step 414, as the mobile client moves into a building,
and known positions of the RF beacons are used to determine the
location of the mobile client. In one example, RSS techniques can
be used.
[0038] Subsequently, at step 416, the mobile client moves within
the building and detects other access points having unknown
locations. The known location of the mobile client can be used to
determine the location of the new RF beacons. At step 418, as the
mobile client moves out of the coverage area of known RF beacons,
the position of the new RF beacons may be used to determine the
location of the mobile client. This approach can be repeated to
determine the positions of additional RF beacons and the subsequent
positions of the mobile client as it enters and then operates
within the coverage areas of the addition RF beacons.
[0039] Referring now to FIG. 5, an example of a device 500 used for
location determination is described. The device 500 includes an
interface 502 and a controller 504. In one example, the device 500
is a mobile client such as a cellular phone, a pager, a personal
digital assistant or a personal computer.
[0040] The interface 502 is adapted and configured to receive first
signals 506 from at least one first signal source (e.g., a
satellite) that operates in a first location determination system
(e.g., a satellite system) and second signals 508 from at least one
second signal source (e.g., an RF beacon) that operates in a second
location determination system (e.g., a WLAN).
[0041] The controller 504 is adapted and arranged to determine the
position of a mobile client at least in part by utilizing the first
signals from the first signal source and is further adapted and
arranged to determine the position of the second signal source by
using both the position of the mobile client and the signals
received from the second signal source.
[0042] The controller 504 may be further adapted and arranged to
determine a third position of the device 500 by utilizing the
second position and third signals from the at least one second
signal source.
[0043] Thus, approaches are provided that substantially
continuously determine the location of a mobile client as the
mobile client moves between or within different types of networks.
The approaches provided allow for the seamless transitioning of the
mobile client between different networks and within networks and
allow for the location of the mobile client to be substantially
continuously known. In so doing, services dependent upon knowing
the location of the mobile client can be effectively provided to
the mobile client. Furthermore, the approaches provided herein are
cost-effective to implement and do not require a costly and time
consuming mapping process to be performed.
[0044] Those skilled in the art will recognize that a wide variety
of modifications, alterations, and combinations can be made with
respect to the above described embodiments without departing from
the spirit and scope of the invention, and that such modifications,
alterations, and combinations are to be viewed as being within the
scope of the invention.
* * * * *