U.S. patent application number 14/221656 was filed with the patent office on 2014-07-24 for methods and apparatuses for providing peer-to-peer positioning in wireless networks.
This patent application is currently assigned to QUALCOMM Incorporated. The applicant listed for this patent is QUALCOMM Incorporated. Invention is credited to Babak Aryan, Seung Hyun Kong, Wenhui Xiong.
Application Number | 20140206386 14/221656 |
Document ID | / |
Family ID | 42537642 |
Filed Date | 2014-07-24 |
United States Patent
Application |
20140206386 |
Kind Code |
A1 |
Aryan; Babak ; et
al. |
July 24, 2014 |
METHODS AND APPARATUSES FOR PROVIDING PEER-TO-PEER POSITIONING IN
WIRELESS NETWORKS
Abstract
Methods and apparatus are provided for use in wireless networks
to provide and/or otherwise support peer-to-peer positioning
operations.
Inventors: |
Aryan; Babak; (San Diego,
CA) ; Kong; Seung Hyun; (Daejeon, KR) ; Xiong;
Wenhui; (Lexington, KY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
QUALCOMM Incorporated |
San Diego |
CA |
US |
|
|
Assignee: |
QUALCOMM Incorporated
San Diego
CA
|
Family ID: |
42537642 |
Appl. No.: |
14/221656 |
Filed: |
March 21, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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12420637 |
Apr 8, 2009 |
8699409 |
|
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14221656 |
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Current U.S.
Class: |
455/456.1 |
Current CPC
Class: |
H04W 64/006 20130101;
G01S 5/0284 20130101; G01S 5/14 20130101; G01S 5/0289 20130101 |
Class at
Publication: |
455/456.1 |
International
Class: |
H04W 64/00 20060101
H04W064/00 |
Claims
1. A method comprising, at a mobile station: receiving a
peer-to-peer trilateration (PPT) request message from another
device over a wireless communication link; determining a current
position fix; receiving at least one of a first PPT beacon signal
from a target mobile station during a first assigned time slot, or
a second PPT beacon signal from said target mobile station during
one of said first assigned time slot or another assigned time slot;
determining at least one of a pseudorange or a path loss based, at
least in part, on at least one of said received first PPT beacon
signal, or said second PPT beacon signal, in response to said PPT
request message; and transmitting at least one report message to
said another device, said at least one report message being
indicative of said current position fix and at least one of said
pseudorange or said path loss.
2. The method as recited in claim 1, wherein said PPT request
message corresponds to a peer-to-peer positioning operation.
3. The method as recited in claim 1, wherein said another device
comprises at least one of a base station, said target mobile
station, or a network resource.
4. The method as recited in claim 1, wherein said PPT request
message is indicative of at least one of said first assigned time
slot, or said another assigned time slot.
5. The method as recited in claim 1, further comprising, at the
mobile station: receiving an acknowledgment message from said
another device ending a peer-to-peer positioning operation.
6. An apparatus for use at a mobile station, the apparatus
comprising: means for receiving a PPT request message from another
device; means for determining a current position fix; means for
receiving at least one of a first PPT beacon signal from a target
mobile station during a first assigned time slot, or a second PPT
beacon signal from said target mobile station during one of said
first assigned time slot or another assigned time slot; means for
determining at least one of a pseudorange or a path loss based, at
least in part, on at least one of said received first PPT beacon
signal, or said second PPT beacon signal, in response to said PPT
request message; and means for transmitting at least one report
message to said another device, said at least one report message
being indicative of said current position fix and at least one of
said pseudorange or said path loss.
7. The apparatus as recited in claim 6, wherein said PPT request
message corresponds to a peer-to-peer positioning operation.
8. The apparatus as recited in claim 6, wherein said another device
comprises at least one of a base station, said target mobile
station, or a network resource.
9. The apparatus as recited in claim 6, wherein said PPT request
message is indicative of at least one of said first assigned time
slot, or said another assigned time slot.
10. The apparatus as recited in claim 6, further comprising: means
for receiving an acknowledgment message from said another device
ending a peer-to-peer positioning operation.
11. A mobile station comprising: memory; a communication interface;
and a processing unit coupled to said memory and said communication
interface, said processing unit to: receive a peer-to-peer
trilateration (PPT) request message from another device via said
communication interface; access a current position fix stored in
said memory; determine at least one of a pseudorange or a path loss
based, at least in part, on at least one of a first PPT beacon
signal received via said communication interface from a target
mobile station during a first assigned time slot, or a second PPT
beacon signal received via said communication interface from said
target mobile station during one of said first assigned time slot,
or another assigned time slot; and initiate transmission of at
least one report message to said another device via said
communication interface, said at least one report message
indicating said current position fix and one or more of said
pseudorange or said path loss, and wherein said at least one report
message is provided in response to said PPT request message.
12. The method as recited in claim 11, wherein said PPT request
message corresponds to a peer-to-peer positioning operation.
13. The method as recited in claim 11, wherein said another device
comprises at least one of a base station, said target mobile
station, or a network resource.
14. The method as recited in claim 11, wherein said PPT request
message is indicative of at least one of said first assigned time
slot, or said another assigned time slot.
15. The method as recited in claim 11, said processing unit to
further: end support of a peer-to-peer positioning operation in
response to an acknowledgment message received via said
communication interface from said another device.
16. An article comprising: a non-transitory computer readable
medium having computer implementable instructions stored thereon
executable by a processing unit of a mobile station to: receive a
peer-to-peer trilateration (PPT) request message from another
device; access a current position fix; determine at least one of a
pseudorange or a path loss based, at least in part, on at least one
of a first PPT beacon signal received from a target mobile station
during a first assigned time slot, or a second PPT beacon signal
received from said target mobile station during one of said first
assigned time slot, or another assigned time slot; and initiate
transmission of at least one report message to said another device,
said at least one report message indicating said current position
fix and one or more of said pseudorange or said path loss, and
wherein said at least one report message is provided in response to
said PPT request message.
17. The article as recited in claim 16, wherein said PPT request
message corresponds to a peer-to-peer positioning operation.
18. The article as recited in claim 16, wherein said another device
comprises at least one of a base station, said target mobile
station, or a network resource.
19. The article as recited in claim 16, wherein said PPT request
message is indicative of at least one of said first assigned time
slot, or said another assigned time slot.
20. The article as recited in claim 16, further comprising computer
implementable instructions which if implemented by the one or more
processing units operatively enables the one or more processing
units to: end support of a peer-to-peer positioning operation in
response to an acknowledgment message received from said another
device.
Description
[0001] This patent application is a divisional of co-pending U.S.
patent application Ser. No. 12/420,637, filed on Apr. 8, 2009,
Titled, "METHODS AND APPARATUSES FOR PROVIDING PEER-TO-PEER
POSITIONING IN WIRELESS NETWORKS", and which is assigned to the
assignee hereof and incorporated herein by reference.
BACKGROUND
[0002] 1. Field
[0003] The subject matter disclosed herein relates to electronic
devices and more particularly to methods and apparatuses for use in
electronic devices for use in wireless communication systems.
[0004] 2. Information
[0005] Wireless communication systems and devices are fast becoming
one of the most prevalent technologies in the digital information
arena. Satellite and cellular telephone services and other like
wireless communication networks may already span the entire globe.
Additionally, new wireless systems (e.g., networks) of various
types and sizes are added each day to provide connectivity between
a plethora of devices, both fixed and portable. Many of these
wireless systems are coupled together through other communication
systems and resources to promote even more communication and
sharing of information. Indeed, it is not uncommon for some devices
to communicate with more than one wireless communication system and
this trend appears to be growing.
[0006] Another popular and increasingly important wireless
technology includes navigation systems and devices and in
particular satellite positioning systems (SPS) such as, for
example, the Global Positioning System (GPS) and other like
Global
[0007] Navigation Satellite Systems (GNSS). An SPS receiver, for
example, may receive wireless SPS signals that are transmitted by a
plurality of orbiting satellites of a GNSS. The SPS signals once
received may be processed, for example, to determine a global time,
an approximate geographical location, altitude, and/or speed
associated with a device having the SPS receiver path, such as, for
example a cellular telephone.
[0008] Other positioning techniques are also known and available
for use in locating a mobile device such as a cellular telephone
within the coverage area of a wireless network. For example,
various signaling/timing techniques may be employed to determine or
otherwise estimate the location of the cellular telephone based on
trilateration and/or other like processes.
SUMMARY
[0009] Methods and apparatus are provided for use in peer-to-peer
positioning operations in wireless networks.
[0010] In accordance with certain aspects, a method may be
implemented at a mobile station, which comprises: receiving a
peer-to-peer trilateration (PPT) request message from another
device over a wireless communication link; determining a current
position fix; receiving at least one of a first PPT beacon signal
from a target mobile station during a first assigned time slot, or
a second PPT beacon signal from the target mobile station during
one of the first assigned time slot or another assigned time slot;
determining at least one of a pseudorange or a path loss based, at
least in part, on at least one of the received first PPT beacon
signal, or the second PPT beacon signal, in response to the PPT
request message; and transmitting at least one report message to
the another device, the at least one report message being
indicative of the current position fix and at least one of the
pseudorange or the path loss.
[0011] In accordance with certain aspects, an apparatus for use at
a mobile station may comprise: means for receiving a PPT request
message from another device; means for determining a current
position fix; means for receiving at least one of a first PPT
beacon signal from a target mobile station during a first assigned
time slot, or a second PPT beacon signal from the target mobile
station during one of the first assigned time slot or another
assigned time slot; means for determining at least one of a
pseudorange or a path loss based, at least in part, on at least one
of the received first PPT beacon signal, or the second PPT beacon
signal, in response to the PPT request message; and means for
transmitting at least one report message to the another device, the
at least one report message being indicative of the current
position fix and at least one of the pseudorange or the path
loss.
[0012] In accordance with certain aspects, a mobile station may
comprise memory, a communication interface, and a processing unit
to: receive a peer-to-peer trilateration (PPT) request message from
another device via the communication interface; access a current
position fix stored in the memory; determine at least one of a
pseudorange or a path loss based, at least in part, on at least one
of a first PPT beacon signal received via the communication
interface from a target mobile station during a first assigned time
slot, or a second PPT beacon signal received via the communication
interface from the target mobile station during one of the first
assigned time slot, or another assigned time slot; and initiate
transmission of at least one report message to the another device
via the communication interface, the at least one report message
indicating the current position fix and one or more of the
pseudorange or the path loss, and wherein the at least one report
message is provided in response to the PPT request message.
[0013] In accordance with certain aspects, an article of
manufacture may comprise a non-transitory computer readable medium
having computer implementable instructions stored thereon
executable by a processing unit of a mobile station to: receive a
peer-to-peer trilateration (PPT) request message from another
device; access a current position fix; determine at least one of a
pseudorange or a path loss based, at least in part, on at least one
of a first PPT beacon signal received from a target mobile station
during a first assigned time slot, or a second PPT beacon signal
received from the target mobile station during one of the first
assigned time slot, or another assigned time slot; and initiate
transmission of at least one report message to the another device,
the at least one report message indicating the current position fix
and one or more of the pseudorange or the path loss, and wherein
the at least one report message is provided in response to the PPT
request message.
BRIEF DESCRIPTION OF DRAWINGS
[0014] FIG. 1 is a block diagram illustrating an example wireless
network that may be enabled to implement a peer-to-peer
trilateration (PPT) scheme in accordance with an
implementation.
[0015] FIG. 2 shows an example information or message flow between
devices in a wireless network, for example, as in FIG. 1, as part
of a PPT scheme in accordance with an implementation.
[0016] FIG. 3 shows an example flow-diagram of a method that may be
implemented in a target mobile station, for example, to perform or
otherwise support a PPT scheme in accordance with an
implementation.
[0017] FIG. 4 shows an example flow-diagram of a method that may be
implemented in a nomadic peer device, for example, to perform or
otherwise support a PPT scheme in accordance with an
implementation.
[0018] FIG. 5 shows an example flow-diagram of a method that may be
implemented in a dedicated peer device, for example, to perform or
otherwise support a PPT scheme in accordance with an
implementation.
[0019] FIG. 6 shows an example flow-diagram of a method that may be
implemented in a base station, for example, to perform or otherwise
support a PPT scheme in accordance with an implementation.
[0020] FIG. 7 shows an example flow-diagram of a method that may be
implemented in a wireless network, for example, to perform or
otherwise support a PPT scheme in accordance with an
implementation.
[0021] FIG. 8 shows an example flow-diagram of a another method
that may be implemented in a wireless network, for example, to
perform or otherwise support a PPT scheme in accordance with an
implementation.
[0022] FIG. 9 is a block diagram illustrating an exemplary device
that may, for example, be included in a wireless network and
operatively enabled to perform or otherwise support at least a
portion of a PPT operation in accordance with an
implementation.
DETAILED DESCRIPTION
[0023] Non-limiting and non-exhaustive aspects are described with
reference to the following figures, wherein like reference numerals
refer to like parts throughout the various figures unless otherwise
specified.
[0024] When a mobile station (MS) is located inside a building
and/or is otherwise located within an environment that in some
manner limits the MS's ability to receive SPS signals, other
techniques may need to be employed to help determine (e.g.,
estimate) the location of the MS. Some example techniques may, for
example, include terrestrial network based solutions, such as
Advanced Forward Link Trilateration (AFLT) or Observed Time
Difference of Arrival (O-TDOA), which utilize the measurements from
pilot channel transmitted by multiple base stations (BSs) to fix
the location of an MS. However, such techniques may not always
provide sufficient accuracy due, for example, to the (sometimes
large) distance between a BS and MS which may lead to multipath
errors in the resulting range measurements.
[0025] The methods and apparatuses described herein may be
implemented as part of a peer-to-peer trilateration scheme that is
referred to herein as a "PPT" scheme that may provide location
information for MSs that are not able to perform SPS position fix
and/or possibly improve position accuracy for a target MS due, for
example, to possibly shorter distances between the target MS and
participating peer devices.
[0026] As will be described in greater detail below, a PPT scheme
may be considered as a positioning technique that uses reverse link
signals transmitted and received by MSs. In many cases, a target MS
may be unable to obtain a fix of its own location using SPS signals
(e.g., using A-GPS) if the MS is inside a building or within an
environment where SPS signals may be severely blocked, attenuated,
and/or otherwise affected in some manner. A PPT scheme may, for
example, be employed to allow a target MS that may be inside a
building or such an environment to transmit at least one "beacon"
signal (e.g., a reverse link signal, access probe signal, and/or
the like) such that peer devices (e.g., other MSs) that may be
located nearby and possibly outside the building/environment may
detect. These peer devices may, for example, measure a time of
arrival (TOA) for the beacon signal. When three or more TOAs are
obtained from three or more peer devices, for example, it may be
possible to determine the location of the target MS. In certain
example implementations, one or more of the peer devices may be
equipped with SPS functions that may synchronize an internal clock
with respect to the SPS signals and/or SPS time.
[0027] Certain example implementations of a PPT scheme may also or
alternatively be enabled to operate such that the peer devices
transmit similar or other like beacon signals and the target MS
measures corresponding TOAs. In both cases, a clock error in the
target MS may lead to a TOA error in all or some of the TOA
measurements, however, such TOA error may be accounted for (e.g.,
cancelled out) by certain positioning techniques, for example, as
provided herein.
[0028] In accordance with certain further aspects described in
greater detail below, a PPT scheme may be enabled to discover,
alert, and/or otherwise determine which peer devices may be
geographically nearby a target MS and possibly available to support
certain PPT operations.
[0029] Position determination techniques described herein may be
used for various wireless communication networks such as a wireless
wide area network (WWAN), a wireless local area network (WLAN), a
wireless personal area network (WPAN), and so on. The term
"network" and "system" are often used interchangeably. A WWAN may
be a Code Division Multiple Access (CDMA) network, a Time Division
Multiple Access (TDMA) network, a Frequency Division Multiple
Access (FDMA) network, an Orthogonal Frequency Division Multiple
Access (OFDMA) network, a Single-Carrier Frequency Division
Multiple Access (SC-FDMA) network, and so on. A CDMA network may
implement one or more radio access technologies (RATs) such as
cdma2000, Wideband-CDMA (W-CDMA), and so on. Cdma2000 includes
IS-95, IS-2000, and IS-856 standards. A TDMA network may implement
Global System for Mobile Communications (GSM), Digital Advanced
Mobile Phone System (D-AMPS), or some other RAT. GSM and W-CDMA are
described in documents from a consortium named "3rd Generation
Partnership Project" (3GPP). Cdma2000 is described in documents
from a consortium named "3rd Generation Partnership Project 2"
(3GPP2). 3GPP and 3GPP2 documents are publicly available. A WLAN
may be an IEEE 802.1 1x network, and a WPAN may be a Bluetooth
network, an IEEE 802.15x, or some other type of network. The
techniques may also be used for any combination of WWAN, WLAN
and/or WPAN.
[0030] A MS (and/or a BS, etc.) may also receive signals from
satellites or the like, which may be from a Global Positioning
System (GPS), Galileo, GLONASS, NAVSTAR, GNSS, a system that uses
satellites from a combination of these systems, or any SPS
developed in the future, each referred to generally herein as a
Satellite Positioning System (SPS).
[0031] Furthermore, the methods and apparatuses described herein
may be used with positioning determination systems that utilize
pseudolites or a combination of satellites and pseudolites.
Pseudolites may include ground-based transmitters that broadcast a
PN code or other ranging code (e.g., similar to a GPS or CDMA
cellular signal) modulated on an L-band (or other frequency)
carrier signal, which may be synchronized with SPS time. Each such
transmitter may be assigned a unique PN code so as to permit
identification by a remote receiver. Pseudolites may be useful in
situations where SPS signals from an orbiting satellite might be
unavailable, such as in tunnels, mines, buildings, urban canyons or
other enclosed areas. Another implementation of pseudolites is
known as radio-beacons. The term "satellite", as used herein, is
intended to include pseudolites, equivalents of pseudolites, and
possibly others. The term "SPS signals", as used herein, is
intended to include SPS-like signals from pseudolites or
equivalents of pseudolites.
[0032] As used herein, a mobile station (MS) refers to a device
such as a cellular or other wireless communication device, personal
communication system (PCS) device, personal navigation device,
Personal Information Manager (PIM), Personal Digital Assistant
(PDA), laptop or other suitable mobile device which may be capable
of receiving wireless communications. The term "mobile station" is
also intended to include devices which communicate with a personal
navigation device (PND), such as by short-range wireless, infrared,
wireline connection, or other connection--regardless of whether
satellite signal reception, assistance data reception, and/or
position-related processing occurs at the device or at the PND.
Also, "mobile station" is intended to include all devices,
including wireless communication devices, computers, laptops, etc.
which are capable of communication with a server, such as via the
Internet, WiFi, or other network, and regardless of whether
satellite signal reception, assistance data reception, and/or
position-related processing occurs at the device, at a server, or
at another device associated with the network. Any operable
combination of the above are also considered a "mobile
station".
[0033] The methodologies described herein may be implemented by
various means depending upon the application. For example, these
methodologies may be implemented in hardware, firmware, software,
or a combination thereof. For a hardware implementation, one or
more processing units may be implemented within one or more
application specific integrated circuits (ASICs), digital signal
processors (DSPs), digital signal processing devices (DSPDs),
programmable logic devices (PLDs), field programmable gate arrays
(FPGAs), processors, controllers, micro-controllers,
microprocessors, electronic devices, other electronic units
designed to perform the functions described herein, or a
combination thereof.
[0034] For a firmware and/or software implementation, the
methodologies may be implemented with modules (e.g., procedures,
functions, and so on) that perform the functions described herein.
Any machine readable medium tangibly embodying instructions may be
used in implementing the methodologies described herein. For
example, software codes may be stored in a memory of a MS, and
executed by a processing unit of the MS. Memory may be implemented
within a processing unit and/or external to the processing unit. As
used herein the term "memory" refers to any type of long term,
short term, volatile, nonvolatile, or other memory and is not to be
limited to any particular type of memory or number of memories, or
type of media upon which memory is stored.
[0035] If implemented in software, the functions that implement the
methodologies or portions thereof may be stored on and/or
transmitted over as one or more instructions or code on a
computer-readable medium. A computer-readable medium may take the
form of an article of manufacture. A computer-readable medium may
include computer storage media and/or communication media including
any medium that facilitates transfer of a computer program from one
place to another. A storage media may be any available media that
may be accessed by a computer or like device. By way of example but
not limitation, a computer-readable medium may comprise RAM, ROM,
EEPROM, CD-ROM or other optical disk storage, magnetic disk storage
or other magnetic storage devices, or any other medium that can be
used to carry or store desired program code in the form of
instructions or data structures and that can be accessed by a
computer. Also, any connection may be properly termed a
computer-readable medium. For example, if the software is
transmitted from a website, server, or other remote source using a
coaxial cable, fiber optic cable, twisted pair, digital subscriber
line (DSL), or wireless technologies such as infrared, radio, and
microwave, then the coaxial cable, fiber optic cable, twisted pair,
DSL, or wireless technologies such as infrared, radio, and
microwave are included in the definition of medium. Disk and disc,
as used herein, may include compact disc (CD), laser disc, optical
disc, digital versatile disc (DVD), floppy disk and blu-ray disc
where disks usually reproduce data magnetically, while discs
reproduce data optically with lasers. Combinations of the above
should also be included within the scope of computer-readable
media.
[0036] "Instructions" as referred to herein relate to expressions
which represent one or more logical operations. For example,
instructions may be "machine-readable" by being interpretable by a
machine for executing one or more operations on one or more data
objects. However, this is merely an example of instructions and
claimed subject matter is not limited in this respect. In another
example, instructions as referred to herein may relate to encoded
commands which are executable by a processing unit having a command
set which includes the encoded commands. Such an instruction may be
encoded in the form of a machine language understood by the
processing unit. Again, these are merely examples of an instruction
and claimed subject matter is not limited in this respect.
[0037] Unless specifically stated otherwise, as apparent from the
following discussion, it is appreciated that throughout this
specification discussions utilizing terms such as "processing,"
"computing," "calculating," "selecting," "forming," "enabling,"
"inhibiting," "locating," "terminating," "identifying,"
"initiating," "detecting," "obtaining," "hosting," "maintaining,"
"representing," "estimating," "reducing," "associating,"
"receiving," "transmitting," "determining" and/or the like refer to
the actions and/or processes that may be performed by a computing
platform, such as a computer or a similar electronic computing
device, that manipulates and/or transforms data represented as
physical electronic and/or magnetic quantities and/or other
physical quantities within the computing platform's processors,
memories, registers, and/or other information storage,
transmission, reception and/or display devices. Such actions and/or
processes may be executed by a computing platform under the control
of machine-readable instructions stored in a storage medium, for
example. Such machine-readable instructions may comprise, for
example, software or firmware stored in a storage medium included
as part of a computing platform (e.g., included as part of a
processing circuit or external to such a processing circuit).
Further, unless specifically stated otherwise, process described
herein, with reference to flow diagrams or otherwise, may also be
executed and/or controlled, in whole or in part, by such a
computing platform.
[0038] Wireless communication networks are widely deployed to
provide various communication services such as voice, data,
messaging, and/or the like. These networks may be capable of
supporting multiple users by sharing various network resources.
Examples of such multiple-access networks include CDMA networks,
TDMA networks, and FDMA networks.
[0039] Because of the E911 mandate and the increased attention of
Location Based Services (LBSs), quite a few mobile location
technologies have been introduced to the market. One of the popular
technologies is A-GPS which uses the GPS to fix the location of a
MS. With A-GPS, the BS may provide the MS with assistant
information so that the MS is able to acquire SPS signals (here,
e.g., GPS signals) from the satellites quicker than conventional
GPS devices. Other technologies, such AFLT and O-TDOA may utilize
the measurements from pilot channel transmitted by multiple BSs to
fix the location of MS. As introduced above, a PPT scheme may use
peer devices (e.g., MSs, etc.) for range measurements and position
fix. In the sections below, some example transaction flows are
presented to illustrate certain aspects and features that may be
enabled as part of a PPT scheme with regard to a target MS, a
plurality of peer devices, and at least one BS.
[0040] Some example collaborations among BS, target MS, and peer
devices (e.g., nomadic and/or dedicated MSs and/or other devices)
will now be presented in accordance with certain PPT schemes. Some
considerations in such a PPT scheme may include determining when to
wake up a nomadic peer device, when a target MS should transmit a
beacon, when the peer devices (both nomadic and dedicated) should
report their measurements, and when the nomadic devices should
switch back from a PPT mode to another (e.g., normal) operation
mode. These and other considerations are addressed below. In the
examples presented herein reference is often made to actions that
may be taken by a BS. It should be recognized, however, that such
actions may actually be performed in whole or part by one or more
other entity(s) within the network which may or may not be part of
a BS in certain example implementations.
[0041] Additional considerations in such a PPT scheme may include
how to identify peer devices that may be used to support the PPT
scheme. This consideration and others will be addressed in still
subsequent sections below.
[0042] Reference is now made to FIG. 1, which is a block diagram
illustrating an example wireless network 100 that may be enabled to
implement a PPT scheme in accordance with an implementation.
[0043] Wireless network 100 in this example includes a plurality of
MSs 102-1, 102-2, 102-3, 102-4, 102-5, 102-6, 102-7, . . . , 102-t.
Here, MS 102-t may represent a target MS whose location is to be
determined (e.g., estimated). MSs 102-1, 102-2, 102-3, 102-4,
102-5, 102-6, and 102-7 may represent a plurality of nomadic peer
devices. Devices 106-1, 106-2, 106-3, and 1-6-4 may represent a
plurality of dedicated peer devices.
[0044] These various devices may be arranged within a coverage area
all or part of which may be serviced by BS 104, and which may be
enabled to coordinate the measurements between target MS 102-t and
the applicable peer devices. Here, for example, an applicable peer
device (nomadic or dedicated) may be enabled to estimate or
otherwise determine a range between itself and target MS 102-t and
send such measurements/information back to BS 104. BS 104 may, for
example, be enabled to collect various measurements/information. BS
104 may be enabled to calculate the position of target MS 102-t,
and/or send received measurements to another network resource
(e.g., another BS, network server, position determination entity
(PDE), and/or or the like) for calculating the position of target
MS 102-t.
[0045] As illustrated by dashed-line cell boundaries in FIG. 1, a
plurality of cells and/or sectors may be operatively established
and/or otherwise enabled.
[0046] Also shown in the example implementation in FIG. 1 is SPS
110, which may transmit SPS signals to various other devices within
network 100.
[0047] FIG. 2 shows an embodiment of an example information or
message flow 200 between a target MS, nomadic peer devices, and BS
for a PPT scheme. Nomadic devices may, for example, include MSs
with SPS (e.g., A-GPS, GPS, etc.) and reverse link (RL)
functionalities. For this example, the BS, may send out a request
message A1 to the target MS initiating a location fix for the
target MS. If the target MS fails to have SPS functionality or is
otherwise unable to provide a position fix based on SPS signals,
the target MS may then send out a request message A2 to the BS
requesting a PPT operation. The message A1 sent by the BS may be
optional if the target MS itself initiates a positioning request.
Thus, in certain implementations the target MS may omit an SPS
position fix and send out a request message A2 directly to BS.
[0048] Having received a request message A2 from the target MS, the
BS may send out a message A3 to request or otherwise inform the
nomadic peer devices that are close to the target MS to participate
in the PPT operation. Message A3 may include, for example, a wake
up command, and may specify a process ID, one or more time slots
for these peer devices to try to receive the target MS's
transmitted beacon, a long code mask for detecting the target MS's
beacon, and/or other configuration information that may be useful
for the target MS and/or peer devices. In response to receiving a
wake up command, a peer device may initiate and/or otherwise
operatively enable/access SPS functionality (e.g., an onboard
A-GPS, GPS engine, etc.). Peer devices that successfully fix their
current positions may try to receive a RL for the beacon
transmitted by the target MS. Peer devices that have not
successfully fixed their current position using SPS signals and/or
are unable to support the requested PPT operation for other
reasons, may, for example, switch back to their previous operation
mode.
[0049] The peer devices that are able to support the requested PPT
and have successfully fixed their locations may, for example,
adequately synchronize local device time to the SPS time, which may
be obtained or otherwise determined from the SPS signals. Such time
synchronization among the peer devices may, for example, allow a
PPT scheme to be implemented in asynchronous networks such as a
Universal Mobile Telecommunication System (UMTS) network that
implements W-CDMA (UMTS).
[0050] Message A3 from the BS may also be received by the target
MS. When the time slot specified by the message A3 is reached, the
target MS may begin transmitting one or more beacons A4. Such
beacons transmission may be timed to end, and/or may be ended if an
acknowledgment message (ACK) AS is received, for example, from the
BS. For example, in cdma2000 network a beacon may include an access
probe on a
[0051] Reverse Access Channel (R-ACH) or a Reverse Enhanced Access
Channel (R-EACH). Within the beacon, the target MS may, for
example, provide transmit power information, a process ID, and/or
other like information, which may enable receiving peer devices to
establish path loss measurements, distinguish the beacon sender,
etc.
[0052] A peer device may be enabled to receive and detect the RL
beacon A4 transmitted by the target MS and to estimate a
pseudorange or other like information associated with the distance
from itself to the target MS. In addition to a pseudorange
measurement or other like information, a peer device may, for
example, be enabled to measure a received signal power and/or
calculate a path loss. Once a peer device detects a beacon sent by
a target MS, the peer device may report certain information to the
BS, for example, via message A6. In message A6, for example, a peer
device may report its own location, pseudo range, path loss
measurements, and/or the like. The BS may use all or portions of
the information received from various peer devices via messages A6
to fix the location of the target MS.
[0053] A peer device may, for example, be enabled to receive the
ACK message AS sent out by the BS. Once a peer device detects an
ACK from the BS, the peer device may stop supporting the PPT
operation and may switch to another operation mode.
[0054] As shown in FIG. 2, the BS may transmit an end of process
message A7 to the target MS (and possibly one or more peer
devices). The end of process message A7 may inform receiving
devices that PPT operation has been ended (e.g., finished). The
target MS's location information may also be included in end of
process message A7. In certain implementations, such target MS's
location information may be embedded in end of process message A7,
for example, using data encryption techniques to provide additional
security for the user of the target MS.
[0055] FIG. 3 shows an example flow-diagram of a method 300 that
may be implemented in target MS 102-t (FIG. 1), for example, to
perform or otherwise support a PPT scheme in accordance with
message flow 200 (FIG. 2).
[0056] At block 302, it may be determined if a location fix is
desired. Here, for example, a location fix (or a PPT operation) may
be requested through a message A1 or a location fix may result from
local initiation within the target MS. At block 302 the target MS
may choose to start directly with a PPT mode (jumping to block 308)
or to first try an SPS mode and/or other like network-based
positioning solutions, such as AFLT for cdma2000.
[0057] At block 304, in this example, an SPS mode may be attempted
and if it fails or is deemed inadequate (e.g., does not meet a
desired accuracy, for example, as may be determined by QOS) then
method 300 may move to block 306 wherein a network-based
positioning solution(s) may be attempted. If the network-based
positioning solution(s) fails or is deemed inadequate (e.g., does
not meet a desired accuracy, for example, as determined by QOS),
then method 300 may move to block 308. At block 308, the target MS
may send a request message A2 to the BS to request the PPT
operation. Block 308 may also be reached from block 302 if PPT is
to start directly.
[0058] At block 310 it may be determined if a message A3 has been
received from the BS confirming the requested PPT operation. At
block 310, if a message A3 has not been received then method 300
may return to block 308. At block 310, if a message A3 has been
received then method 300 may continue at block 312.
[0059] Message A3 may, for example assign one or more time slots
during which the target MS may transmit beacon A4. At block 312,
the target MS waits until an assigned time slot occurs. At block
314, the target MS may transmit beacon A4, for example, during all
or part of the assigned time slot. In certain example
implementations beacon A4 may include and/or be similar to an
access probe or the like, e.g., in cdma2000.
[0060] At block 320, the target MS may wait for a period of time
(e.g., a preset or random period of time, or a null or otherwise
nominal period of time) while checking for an ACK AS message.
[0061] At block 316, it may be determined if the target MS has
received an ACK AS message from the base station (or perhaps from
other devices). If an ACK AS message has not been received, then
method 300 may return to block 314 to transmit another beacon,
perhaps with increased transmission power during the same time
slot, or may return to block 312 to transmit another beacon in one
or more subsequent assigned time slot(s). If an ACK AS message has
been received, then at block 318, the target MS may determine
whether to wait until a next time slot. If `Yes` at block 318, then
method 300 may return to block 312, otherwise, if "No" then method
may end.
[0062] FIG. 4 shows an example flow-diagram of a method 400 that
may be implemented in a nomadic peer device, such as, MS 102-1
(FIG. 1), for example, to perform or otherwise support a PPT scheme
in accordance with message flow 200 (FIG. 2).
[0063] At block 402 a wake up command or like A3 message may be
received. At block 404, the nomadic peer device may initiate or
otherwise access an SPS (e.g., A-GPS, GPS, etc.) engine or other
like functionality (or available information) to try to fix its own
location and possibly synchronize (as may be needed) to SPS time.
At block 406 it may be determined if the peer device has been
successful in fixing its own location (and, as applicable
synchronizing to SPS time). If the peer device has not been
successful in fixing its own location (and, as applicable
synchronizing to SPS time), then method 400 may end. If the peer
device has been successful in fixing its own location (and, as
applicable synchronizing to SPS time), then method 400 may continue
at block 407. At block 407, method 400 may include waiting for a
timeslot in case the BS has configured the target mobile to
transmit diversity beacons.
[0064] At block 408, the peer device may attempt to receive
("listen" to) a RL beacon A4 transmitted by the target MS. Here,
for example, a peer device may wait for an assigned time slot to
occur, during which such beacon A4 is expected to be transmitted.
At block 410 it may be determined if a beacon A4 has been received.
If a beacon A4 has been received, then at block 414 the peer device
may transmit (report, record, etc.) its own location, and measured
pseudorange, path loss, and/or the like to the BS (e.g., via a
message A6), at which point method 400 may continue at block 413.
If a beacon A4 has not been received, then method 400 may continue
at block 412 wherein it may be determined if an assigned time slot
has expired and/or if an ACK AS message has been received (e.g.,
over a forward link (FL)). If an assigned time slot for the PPT
operation has expired and/or an ACK A5 message received, then
method 400 may continue at block 413. If an assigned time slot for
the PPT operation has not expired and no ACK A5 message received,
then method 400 may continue at block 408.
[0065] At block 413, method 400 may decide to wait for the next
timeslot. If "Yes" at block 413, then method 400 may return at
block 407. If "No" at block 413, then method 400 may continue at
block 416. At block 416, the peer device may report its own
location with pseudorange and path loss measurements to BS in
message A6. Method 400 may end after block 416.
[0066] In certain implementations, it may be beneficial and/or
convenient to use one or more dedicated peer devices 106 (FIG. 1)
to support a PPT operation. A dedicated peer device may, for
example, be deployed at certain locations and dedicated for range
and path loss measurements. These dedicated peer devices may also
have the SPS functionality and synchronize themselves to the SPS
time (as the need may be). These dedicated devices, furthermore,
may either continually monitor the RL for beacons or monitor the RL
on preconfigured intervals as set and optimized by the network. It
should be recognized that in certain implementations the
coordination between a dedicated peer device and the BS may be less
than that of nomadic peer devices, as messages A3 and/or A5 from BS
(FIG. 2) may not be needed for dedicated peer devices.
[0067] In another embodiment, the nomadic peer devices may have
been "preconfigured", as they entered the current cell served by BS
104 (FIG. 1), to monitor the RL for beacons at regular intervals
and preset time slot durations as set and optimized by the network.
It should be recognized that in this example the coordination
between the nomadic peer devices and the BS may not use messages A3
and/or A5 from BS (FIG. 2.)
[0068] With this in mind, FIG. 5 shows an example flow-diagram of a
method 500 that may be implemented in a dedicated peer device or
"preconfigured" nomadic peer device, such as, device 106-1 (FIG.
1), for example, to perform or otherwise support a PPT scheme in
accordance with message flow 200 (FIG. 2). As illustrated in FIG.
5, blocks 404 and 406 may be included in certain implementations as
part of method 500.
[0069] Method 500 may, for example, be implemented for devices
enabled to support a preconfigured timeslot operation. Thus, in
this example method 500, wait times t.sub.1 & t.sub.2, and a
timeslot duration of t.sub.3 have been included. In certain
implementations, t.sub.1 may be zero (e.g., to correspond to
continuous GPS tracking), t.sub.2 may be zero, and/or t.sub.3 may
be infinite (e.g., to correspond to always monitoring for A4
beacons). In still other example implementations, t.sub.1 may be
equal or about equal to the sum of t.sub.2 and t.sub.3.
[0070] Thus, as illustrated in FIG. 5, at block 503 a wait time
t.sub.1 may be introduced between block 406 and 404. At block 501,
a wait time t.sub.2 may be introduced between block 406 and
502.
[0071] At block 502 in this example, a dedicated or "preconfigured"
nomadic peer device may be enabled to receive a transmitted beacon
A4 as may be transmitted by the target MS on the RL. At block 504
it may be determined if a beacon A4 has been received. If a beacon
A4 has not been received, then method 500 may continue at block
505. If a beacon A4 has been received, then method 500 may continue
at block 507. At block 507, the peer device may record pseudorange
and path loss measurements for transmission to BS in message A6,
and method 500 may continue at block 505.
[0072] At block 505, it may be determined if a timeslot duration of
t.sub.3 has expired or if N measurements have been collected. N may
equal 1 or more. Here, for example, parameter N may be implemented
to reflect the number of measurements that may be collected by the
peer device (fixed or nomadic) and reported in a transmission to
the BS. Such parameter N may, for example, be implanted in a manner
to operatively control the number of messages that a peer device
may need to transmit to a BS. If "No" at block 505, then method 500
may return at block 502. If "Yes" at block 505, then method 500 may
continue at block 506.
[0073] At block 506, wherein the dedicated or "preconfigured"
nomadic peer device may report (e.g., via report message A6) its
own location (if needed), measured pseudo range, path loss
measurements, and/or the like to the BS, along with a process ID
and/or the like to identify the beacon A4 that was received.
[0074] It is worth noting that in message A6, the location
information of the dedicated devices may be optional. For example,
the location information of the dedicated devices may be reported
either once as powered on, and/or every T seconds (where, for
example, T is a system optimization parameter).
[0075] FIG. 6 shows an example flow-diagram of a method 600 that
may be implemented in a base station, such as, BS 104 (FIG. 1), for
example, to perform or otherwise support a PPT scheme in accordance
with message flow 200 (FIG. 2).
[0076] At block 602, the BS may transmit a position request message
A1 to a target MS. Here, for example, the BS may transmit a
position request message A1 in response to a request for location
information for the target MS from one or more other network
resources. At block 604, the BS may receive a PPT operation request
A2 from the target MS. At block 606, the BS may assign one or more
process time slots to the PPT operation.
[0077] At block 608, the BS may transmit a message A3, which may,
for example, include a PPT wake up command for a plurality of
nomadic peer devices, specify one or more time slots for target MS
and peer devices, specify a long code mask for detecting a target
MS's beacon, specify a process ID, and/or specify other
configurations/information as may be useful for the PPT
operation.
[0078] At block 610, the BS may receive a beacon A4 transmitted by
the target MS. At block 612, the BS may transmit an ACK message A5.
At block 614, the BS may receive information reported, as may be
transmitted via messages A6, from the various peer devices that
supported the PPT operation.
[0079] At block 616, it may be determined if the BS has received
enough information from the peer devices to allow calculating the
location of the target MS. If enough information has not been
received from the peer devices, then method 600 may continue at
block 618 wherein the BS may determine whether the assigned time
slot(s) have expired. If the assigned time slot(s) have not
expired, then method 600 may continue at block 614. If the assigned
time slot(s) have expired, then method 600 may continue at block
606, for example. If at block 616 it is determined that enough
information has been received from the peer devices, then method
600 may continue at block 620 wherein the location of the target MS
may be calculated by a network entity (such as PDE, location
server, and/or the like). Here, at this stage certain information
available within the network, such as, e.g., previous A-GPS or AFLT
measurements, may be combined and used as applicable in determining
a final location calculation. At block 622, the BS may transmit
and/or otherwise provide the calculated location information for
the target MS to one or more other network resources, as may be
applicable. At block 622, the BS may transmit calculated location
information to the target MS, for example, embedded in a message A7
that may also serve to inform the target MS that the PPT operation
has ended.
[0080] In the sections below, some example techniques are described
which may be implemented as part of a PPT scheme to discover,
alert, and/or otherwise determine which peer devices (e.g., nomadic
and/or dedicated) may be geographically nearby a target MS and
possibly available to support a PPT operation.
[0081] In accordance with certain aspects, a PPT scheme may be
implemented to make a BS aware of which peer devices may be nearby
a target MS and possibly available to support a PPT operation. For
example, in certain implementations, a PDE and/or other like
location server may be enabled to make the BS aware of devices that
support a PPT operation. Here, for example, a BS may be enabled to
try to target message A3 for peer devices near a target device
based on a coarse location estimate for the target MS. Since the
target MS may not have a SPS location fix, a coarse location
estimate may be attempted using another location technology such as
AFLT, a signal strength based positioning method, etc. If such
other location technologies are unsuccessful or otherwise
unavailable, then the BS may be enabled to determine which sectors
or cells are associated with the target MS. Once a coarse location
estimate has been established for a target MS, the network (e.g., a
BS, location server, and/or other like devices) may determine which
peer devices may be located in the vicinity of the target MS and/or
otherwise available to possibly support a PPT operation. For
example, the network may determine or otherwise access location
estimates of peer devices nearby the coarse location estimate. This
discovery process may include requesting location fixes for one or
more peer devices, and/or accessing other network resources to
determine locations and/or course location estimates for the peer
devices.
[0082] The network may be enabled to select a plurality (N) of peer
devices (N) that are located nearby the target MS. The number N
may, for example, be a function of uncertainty of the location
estimates of the target MS and/or peer devices. In certain example
implementations, N should be at least three (N=3) if not greater.
If the confidence level of location estimate of the target MS is
deemed low or AFLT is not successful, then the coarse location
estimate of the target MS may include an entire sector (or cell)
area in which case N may be as large as the number of all outdoor
MSs within the sector (or cell). In some cases if the target MS
seems to be located at a sector (or cell) boundary, then N may be
as large as the number of peer devices within the neighbor sectors
(or cells). Thus, in many cases N may be much larger than
three.
[0083] FIG. 7 shows an example flow-diagram of a method 700 that
may be implemented in wireless network 100 (FIG. 1), for example,
to perform or otherwise support a PPT operation.
[0084] At block 702, a target MS may attempt to determine at least
a coarse location estimate for itself, for example, based on AFLT
and/or other network-based positioning solution(s). At block 704 it
may be determined if such location estimates were successful. If
such location estimates were successful, then method 700 may
continue at block 706 wherein it may be determined which sectors
(or cells) may cover the vicinity of the target MS based on its
coarse location estimates. If at block 704 it is determined that
such coarse location estimates were not successful, then method 700
may continue at block 708 wherein it may be determined which
neighbor sectors (or cells) may be in the vicinity of the target
MS. At block 710, at least a portion of the peer devices available
in the neighbor sectors/cells may be selected to support the PPT
operation.
[0085] At block 712, a determination may be made as to whether
there may be any nearby peer devices in the sectors/cells
determined at block 706. If there are enough nearby peer devices in
the vicinity of the target MS in the sectors/cells determined at
block 706, then at block 718 at least a portion of the peer devices
available in such sectors/cells may be selected to support the PPT
operation. If at block 712 there is not information available to
determine any nearby peer devices and/or enough nearby peer devices
in the vicinity of the target MS in the sectors/cells determined at
block 706, then at block 714 an attempt may be made, which in one
embodiment might be done autonomously by the peer devices
themselves, to determine at least coarse location estimations for
nearby peer devices in the sectors/cells determined at block 706.
At block 716 at least a portion of these nearby peer devices that
may be in the vicinity of the target MS may select or may be
selected to support the PPT operation.
[0086] Thus, by way of example but not limitation, in certain
example implementations, a network (e.g., combination of BS, PDE,
location server, etc.) may be enabled to determine which
sector/cell a target device is in, send a message to all or
selected peer devices requesting a position fix, wherein, for
example, such peer devices may perform a position fix and report
back to the network. The network may receive such position fixes
and determine which peer devices may be within the vicinity of the
target device. The network may then send another message to such
peer devices to participate in a PPT operation,
[0087] In certain other example implementations, a peer discovery
operation may be performed which enables one or more peer devices
to decide whether to participate in a PPT operation. Here, for
example, a network may be enabled to determine which sector/cell a
target device is in and send a message (e.g., A3 in FIG. 2) to all
or selected peer devices in the same sector/cell or close thereto
alerting the peer devices of an upcoming PPT operation and
informing them of the coarse location of the target device. These
peer devices may then attempt to perform a position fix (if
desired/needed) and/or otherwise determine whether they are in an
adequately open sky environment, within the vicinity of the target
device to participate in the PPT transaction, and/or take into
account other operational factors. As such, in certain situations,
it may be that only a subset of peer devices decides to participate
in the PPT operation. Those peer devices that do decide to
participate, may report their measurements back to the network
(e.g., using message A6 in FIG. 2).
[0088] In still other example, implementations, the network may
attempt to make a determination of the peer devices within the
vicinity of the target device only if there is enough "relevant"
information available. Such an implementation, for example, may
work well in an LDC, inGeo.TM. system, and/or the like. Here, for
example, the network may search through position reports available
to it within the past `t` seconds, and if there are enough reports
(e.g., N>3) of peer devices within the vicinity of the target
device, the network may selectively send a message (e.g., A3 in
FIG. 2) to those peer devices.
[0089] Thus, by way of further example, a method 800 is shown in
FIG. 8. Here, at block 802 a PPT request (A2) may be received with
a coarse location estimate from the target MS. At block 804, the
sector/cell that the target MS belongs to (e.g., is currently
operating within) may be determined At block 806, a database or
other like information repository may be accessed and checked to
determine if any peer devices in the neighboring sectors/cells may
have recently reported their position within the last `t` seconds.
At decision block 808, it may be determined if at least a portion
(e.g., N>3) of the peer devices are believed to be within the
vicinity of the target device (MS). If the decision is NO, then
method 800 may continue at block 810. If the decision is YES, then
method 800 may continue at block 814.
[0090] At block 810, a message (A3) may be transmitted (in some
implementations, broadcast), which may include the course location
or the like of the target device to peer devices within the same
sector/cell as the target and (as applicable) within applicable
neighboring sectors/cells. At block 812, such peer devices may
perform an SPS fix and at least a portion (e.g., N') may
autonomously decide to support and hence participate in the PPT
operation.
[0091] Back at block 814, a message (A3) may be sent to the N peer
devices requesting that they participate in the PPT operation.
[0092] From either block 812 or 814, method 800 continues with
block 816. At block 816, peer devices that are participating in the
PPT operation may perform range measurements based on the beacon
received from the target device (MS) and report the measurements
back to the network.
[0093] FIG. 9 is a block diagram illustrating an exemplary device
900 that may, for example, be included in wireless network 100
(FIG. 1) and operatively enabled to perform or otherwise support at
least a portion of the example PPT operations described herein.
[0094] Device 900 may, for example, include one or more processing
units 902, memory 904, communication interface 910, an (optional)
SPS receiver 930, which may be operatively coupled with one or more
connections 906 (e.g., buses, lines, fibers, links, etc.).
[0095] Processing unit 902 may be implemented in hardware,
software, or a combination of hardware and software. Thus, for
example, processing unit 902 may represent one or more circuits
configurable to perform at least a portion of a data computing
procedure or process. By way of example but not limitation,
processing unit 902 may include one or more processors,
controllers, microprocessors, microcontrollers, application
specific integrated circuits, digital signal processors,
programmable logic devices, field programmable gate arrays, and the
like, or any combination thereof.
[0096] Memory 904 may represent any data storage mechanism. Memory
904 may include, for example, a primary memory and/or a secondary
memory. Primary memory may include, for example, a random access
memory, read only memory, etc. While illustrated in this example as
being separate from processing unit 902, it should be understood
that all or part of a primary memory may be provided within or
otherwise co-located/coupled with processing unit 902. Secondary
memory may include, for example, the same or similar type of memory
as primary memory and/or one or more data storage devices or
systems, such as, for example, a disk drive, an optical disc drive,
a tape drive, a solid state memory drive, etc.
[0097] In certain implementations, secondary memory may be
operatively receptive of, or otherwise configurable to couple to,
computer readable medium 920. As such, in certain example
implementations, the methods and/or apparatuses presented herein
may take the form in whole or part of a computer readable medium
920 that may include computer implementable instructions 908 stored
thereon, which if executed by at least one processing unit 902 may
be operatively enabled to perform all or portions of the example
peer-to-peer trilateration operations (e.g., PPT operations) as
described herein. Such computer implementable instructions 908 may
also be provided by memory 904, as also illustrated in this
example.
[0098] Memory 904 may also include data 922 that may be associated
with one or more of the example peer-to-peer trilateration
operations (e.g., PPT operations), messages, etc., as described
herein.
[0099] Communication interface 910 may, for example, include one or
more receivers 912 and a transmitter 914, and/or combination
thereof. As shown, communication interface 910 may be operatively
enabled to communicate over wireless links.
[0100] SPS receiver 930, which may be optional in certain
implementations, may be enabled to receive SPS signals, establish a
location fix based at least in part on the SPS signals, and in
certain cases support synchronizing a local clock (not shown) to an
SPS time.
[0101] While there has been illustrated and described what are
presently considered to be example features, it will be understood
by those skilled in the art that various other modifications may be
made, and equivalents may be substituted, without departing from
claimed subject matter. Additionally, many modifications may be
made to adapt a particular situation to the teachings of claimed
subject matter without departing from the central concept described
herein.
[0102] Therefore, it is intended that claimed subject matter not be
limited to the particular examples disclosed, but that such claimed
subject matter may also include all aspects falling within the
scope of appended claims, and equivalents thereof.
* * * * *