U.S. patent application number 13/962940 was filed with the patent office on 2014-10-23 for method for performing timing measurement for location estimation of an electronic device with aid of one request sent to multiple peer devices, and associated apparatus.
This patent application is currently assigned to MEDIATEK INC.. The applicant listed for this patent is MEDIATEK INC.. Invention is credited to Tsai-Yuan Hsu, Shih-Chang Su.
Application Number | 20140315572 13/962940 |
Document ID | / |
Family ID | 51729392 |
Filed Date | 2014-10-23 |
United States Patent
Application |
20140315572 |
Kind Code |
A1 |
Hsu; Tsai-Yuan ; et
al. |
October 23, 2014 |
METHOD FOR PERFORMING TIMING MEASUREMENT FOR LOCATION ESTIMATION OF
AN ELECTRONIC DEVICE WITH AID OF ONE REQUEST SENT TO MULTIPLE PEER
DEVICES, AND ASSOCIATED APPARATUS
Abstract
A method and apparatus for performing timing measurement for
location estimation of an electronic device are provided, where the
method includes the steps of: sending a pre-association broadcast
request frame to trigger multiple responders in a wireless network
system to initiate timing measurement; and performing timing
measurement according to a plurality of timestamps, for determining
a location of the electronic device, wherein for a specific
responder of the responders, a first timestamp and a second
timestamp within the plurality of timestamps respectively
correspond to a time of departure (ToD) and a time of arrival (ToA)
of a pre-association uni-cast response frame received from the
specific responder, and a third timestamp and a fourth timestamp
within the plurality of timestamps respectively correspond to a ToD
and a ToA of an acknowledgement frame corresponding to the
pre-association uni-cast response frame, the acknowledgement frame
sent from the electronic device to the specific responder.
Inventors: |
Hsu; Tsai-Yuan; (Hsinchu
County, TW) ; Su; Shih-Chang; (Hsinchu County,
TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MEDIATEK INC. |
Hsin-Chu |
|
TW |
|
|
Assignee: |
MEDIATEK INC.
Hsin-Chu
TW
|
Family ID: |
51729392 |
Appl. No.: |
13/962940 |
Filed: |
August 8, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61813198 |
Apr 18, 2013 |
|
|
|
Current U.S.
Class: |
455/456.1 |
Current CPC
Class: |
H04W 64/006 20130101;
G01S 5/0205 20130101; G01S 5/10 20130101; G01S 5/14 20130101; H04W
64/00 20130101 |
Class at
Publication: |
455/456.1 |
International
Class: |
G01S 5/10 20060101
G01S005/10 |
Claims
1. A method for performing timing measurement for location
estimation of an electronic device, the method being applied to the
electronic device, the method comprising the steps of: sending a
pre-association broadcast request frame to trigger multiple
responders in a wireless network system to initiate timing
measurement; and performing timing measurement according to a
plurality of timestamps, for determining a location of the
electronic device, wherein a portion of the plurality of timestamps
is obtained from the responders, wherein at least one timestamp is
determined based on a pre-association uni-cast response frame
received from one of the responders; wherein no actual association
is established between the electronic device and any of the
responders.
2. The method of claim 1, wherein a portion of the plurality of
timestamps is determined within the electronic device.
3. The method of claim 1, wherein for a specific responder of the
responders, a first timestamp and a second timestamp within the
plurality of timestamps respectively correspond to a time of
departure (ToD) and a time of arrival (ToA) of a pre-association
uni-cast response frame received from the specific responder, and a
third timestamp and a fourth timestamp within the plurality of
timestamps respectively correspond to a ToD and a ToA of an
acknowledgement frame corresponding to the pre-association uni-cast
response frame received from the specific responder, the
acknowledgement frame sent from the electronic device to the
specific responder.
4. The method of claim 3, wherein the step of performing timing
measurement according to the plurality of timestamps for
determining the location of the electronic device further
comprises: determining a time of flight (ToF) relative to the
specific responder based on the equation of:
ToF=((t4-t1)-(t3-t2))/2; wherein the notations "t1", "t2", "t3",
and "t4" represent the first timestamp, the second timestamp, the
third timestamp, and the fourth timestamp, respectively.
5. The method of claim 4, wherein the step of performing timing
measurement according to the plurality of timestamps for
determining the location of the electronic device further
comprises: determining a distance between the electronic device and
the specific responder based on the equation of: D=(c*ToF); wherein
the notation "D" represents the distance between the electronic
device and the specific responder, and the notation "c" represents
the speed of light in vacuum; and the distance between the
electronic device and the specific responder is utilized for
determining the location of the electronic device.
6. The method of claim 1, wherein the pre-association broadcast
request frame is a probe request frame, and the pre-association
uni-cast response frame is a probe response frame.
7. The method of claim 1, wherein the pre-association broadcast
request frame is a Generic Advertisement Service (GAS) request
frame, and the pre-association uni-cast response frame is a GAS
response frame.
8. An apparatus for performing timing measurement for location
estimation of an electronic device, the apparatus comprises at
least one portion of the electronic device, the apparatus
comprising: a transceiver arranged to transmit or receive
information for the electronic device; and a processing circuit,
coupled to the transceiver, arranged to control operations of the
electronic device, wherein the processing circuit sends, by
utilizing the transceiver, a pre-association broadcast request
frame to trigger multiple responders in a wireless network system
to initiate timing measurement, and performs timing measurement
according to a plurality of timestamps, for determining a location
of the electronic device, wherein a portion of the plurality of
timestamps is obtained from the responders, wherein at least one
timestamp is determined based on a pre-association uni-cast
response frame received from one of the responders; wherein no
actual association is established between the electronic device and
any of the responders.
9. The apparatus of claim 8, wherein a portion of the plurality of
timestamps is determined within the electronic device.
10. The apparatus of claim 8, wherein for a specific responder of
the responders, a first timestamp and a second timestamp within the
plurality of timestamps respectively correspond to a time of
departure (ToD) and a time of arrival (ToA) of a pre-association
uni-cast response frame received from the specific responder, and a
third timestamp and a fourth timestamp within the plurality of
timestamps respectively correspond to a ToD and a ToA of an
acknowledgement frame corresponding to the pre-association uni-cast
response frame received from the specific responder, the
acknowledgement frame sent from the electronic device to the
specific responder.
11. The apparatus of claim 10, wherein the processing circuit
determines a time of flight (ToF) relative to the specific
responder based on the equation of: ToF=((t4-t1)-(t3-t2))/2;
wherein the notations "t1", "t2", "t3", and "t4" represent the
first timestamp, the second timestamp, the third timestamp, and the
fourth timestamp, respectively.
12. The apparatus of claim 11, wherein the processing circuit
determines a distance between the electronic device and the
specific responder based on the equation of: D=(c*ToF); wherein the
notation "D" represents the distance between the electronic device
and the specific responder, and the notation "c" represents the
speed of light in vacuum; and the distance between the electronic
device and the specific responder is utilized for determining the
location of the electronic device.
13. The apparatus of claim 8, wherein the pre-association broadcast
request frame is a probe request frame, and the pre-association
uni-cast response frame is a probe response frame.
14. The apparatus of claim 8, wherein the pre-association broadcast
request frame is a Generic Advertisement Service (GAS) request
frame, and the pre-association uni-cast response frame is a GAS
response frame.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 61/813,198, which was filed on Apr. 18, 2013, and
is included herein by reference.
BACKGROUND
[0002] The present invention relates to location estimation with a
reduced number of frame exchanges between electronic devices in a
wireless network system, and more particularly, to a method for
performing timing measurement for location estimation of an
electronic device, and to an associated apparatus.
[0003] According to the related art, a conventional electronic
device in a wireless network system can be designed to determine
the location of the conventional electronic device in a situation
where the locations of three points in the wireless network system
and the time of flight (or the time of electromagnetic wave
propagation) between the conventional electronic device and each of
the three points are known. However, some problems may occur. For
example, multiple requests are required for triggering the timing
measurement corresponding to the aforementioned three points,
respectively. In another example, before performing the timing
measurement respectively corresponding to the aforementioned three
points, it is typically required to send additional probe frames
from the conventional electronic device to discover peer devices in
the wireless network system, causing the power consumption of the
conventional electronic device to be increased. More particularly,
as the number of frame exchanges for the timing measurement is
typically proportional to the number of peer devices under
consideration and the frequency of updates, the total channel
capacity of the wireless network system may be insufficient in some
situations (e.g. the frequency of updates increases, and/or the
number of users who need positioning in the wireless network system
is many). Thus, a novel method is required for improving the
location estimation of an electronic device in a wireless network
system.
SUMMARY
[0004] It is an objective of the claimed invention to provide a
method for performing timing measurement for location estimation of
an electronic device, and to an associated apparatus, in order to
solve the above-mentioned problems.
[0005] It is another objective of the claimed invention to provide
a method for performing timing measurement for location estimation
of an electronic device, and to an associated apparatus, in order
to reduce the number of frame exchanges in a wireless network
system.
[0006] According to at least one preferred embodiment, a method for
performing timing measurement for location estimation of an
electronic device is provided, where the method comprises the steps
of: sending a pre-association broadcast request frame to trigger
multiple responders in a wireless network system to initiate timing
measurement; and performing timing measurement according to a
plurality of timestamps, for determining a location of the
electronic device, wherein a portion of the plurality of timestamps
is obtained from the responders. For example, at least one
timestamp is determined based on a pre-association uni-cast
response frame received from one of the responders, wherein no
actual association is established between the electronic device and
any of the responders. More particularly, for a specific responder
of the responders (e.g. the aforementioned one of the responders),
a first timestamp and a second timestamp within the plurality of
timestamps respectively correspond to a time of departure (ToD) and
a time of arrival (ToA) of a pre-association uni-cast response
frame received from the specific responder, and a third timestamp
and a fourth timestamp within the plurality of timestamps
respectively correspond to a ToD and a ToA of an acknowledgement
frame corresponding to the pre-association uni-cast response frame
received from the specific responder, the acknowledgement frame
sent from the electronic device to the specific responder. For
example, the pre-association broadcast request frame can be a probe
request frame, and the pre-association uni-cast response frame
received from the specific responder can be a probe response frame.
In another example, the pre-association broadcast request frame can
be a Generic Advertisement Service (GAS) request frame, and the
pre-association uni-cast response frame received from the specific
responder can be a GAS response frame.
[0007] According to at least one preferred embodiment, an apparatus
for performing timing measurement for location estimation of an
electronic device is provided, where the apparatus comprises at
least one portion of the electronic device. The apparatus comprises
a processing circuit arrange to control operations of the
electronic device, and further comprises a transceiver arranged to
transmit or receive information for the electronic device, where
the processing circuit is coupled to the transceiver. In addition,
the processing circuit sends, by utilizing the transceiver, a
pre-association broadcast request frame to trigger multiple
responders in a wireless network system to initiate timing
measurement, and performs timing measurement according to a
plurality of timestamps, for determining a location of the
electronic device, wherein a portion of the plurality of timestamps
is obtained from the responders. For example, at least one
timestamp is determined based on a pre-association uni-cast
response frame received from one of the responders, wherein no
actual association is established between the electronic device and
any of the responders. More particularly, for a specific responder
of the responders (e.g. the aforementioned one of the responders),
a first timestamp and a second timestamp within the plurality of
timestamps respectively correspond to a ToD and a ToA of a
pre-association uni-cast response frame received from the specific
responder, and a third timestamp and a fourth timestamp within the
plurality of timestamps respectively correspond to a ToD and a ToA
of an acknowledgement frame corresponding to the pre-association
uni-cast response frame received from the specific responder, the
acknowledgement frame sent from the electronic device to the
specific responder. For example, the pre-association broadcast
request frame can be a probe request frame, and the pre-association
uni-cast response frame received from the specific responder can be
a probe response frame. In another example, the pre-association
broadcast request frame can be a GAS request frame, and the
pre-association uni-cast response frame received from the specific
responder can be a GAS response frame.
[0008] It is an advantage of the present invention that the present
invention method and apparatus can use merely one request (more
particularly, a request sent from the electric device to multiple
peer devices) to immediately start performing timing measurement
for location estimation. In addition, in comparison with the
related art, the number of frame exchanges in a wireless network
system is greatly reduced, where additional probe frames are not
required. As a result, the power consumption can be decreased, and
the problem of insufficiency of the total channel capacity of the
wireless network system can be prevented.
[0009] These and other objectives of the present invention will no
doubt become obvious to those of ordinary skill in the art after
reading the following detailed description of the preferred
embodiment that is illustrated in the various figures and
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a diagram of an apparatus for performing timing
measurement for location estimation of an electronic device
according to a first embodiment of the present invention.
[0011] FIG. 2 illustrates a wireless network system comprising the
aforementioned electronic device according to an embodiment of the
present invention.
[0012] FIG. 3 illustrates a flowchart of a method for performing
timing measurement for location estimation of an electronic device
according to an embodiment of the present invention.
[0013] FIG. 4 illustrates a control scheme involved with the method
shown in FIG. 3 according to an embodiment of the present
invention.
DETAILED DESCRIPTION
[0014] Certain terms are used throughout the following description
and claims, which refer to particular components. As one skilled in
the art will appreciate, electronic equipment manufacturers may
refer to a component by different names. This document does not
intend to distinguish between components that differ in name but
not in function. In the following description and in the claims,
the terms "include" and "comprise" are used in an open-ended
fashion, and thus should be interpreted to mean "include, but not
limited to . . . ". Also, the term "couple" is intended to mean
either an indirect or direct electrical connection. Accordingly, if
one device is coupled to another device, that connection may be
through a direct electrical connection, or through an indirect
electrical connection via other devices and connections.
[0015] Please refer to FIG. 1, which illustrates a diagram of an
apparatus 100 for performing timing measurement for location
estimation of an electronic device according to a first embodiment
of the present invention, where the apparatus 100 may comprise at
least one portion (e.g. a portion or all) of the electronic device.
For example, the apparatus 100 may comprise a portion of the
electronic device mentioned above, and more particularly, can be at
least one hardware circuit such as at least one integrated circuit
(IC) within the electronic device. In another example, the
apparatus 100 can be the whole of the electronic device mentioned
above. In another example, the apparatus 100 may comprise a system
comprising the electronic device mentioned above (e.g. an
audio/video system comprising the electronic device). Examples of
the electronic device may include, but not limited to, a mobile
phone (e.g. a multifunctional mobile phone), a personal digital
assistant (PDA), and a personal computer such as a laptop
computer.
[0016] As shown in FIG. 1, the apparatus 100 may comprise a
processing circuit 110 arrange to control operations of the
electronic device, and may further comprise a transceiver 120
arranged to transmit or receive information for the electronic
device, where the transceiver 120 is coupled to the processing
circuit 110, and one or more antennas of the electronic device may
be coupled to the transceiver 120. For example, the processing
circuit 110 may comprise at least one processor and associated
hardware resources, and the transceiver 120 may comprise a
transmitter and a receiver such as those for wireless network
communications, where the processor may execute some program codes
110P retrieves from a storage module (e.g. a hard disk drive (HDD),
or a non-volatile memory such as a Flash memory) within the
electronic device to control the aforementioned operations of the
electronic device.
[0017] According to this embodiment, the processing circuit 110 may
send, by utilizing the transceiver 120, a pre-association broadcast
request frame to trigger some peer devices in a wireless network
system to initiate timing measurement. The peer devices may respond
to the pre-association broadcast request frame by sending
pre-association uni-cast response frames to the electronic device,
respectively, so the aforementioned timing measurement can be
performed immediately. Thus, the electronic device can be regarded
as the initiator, and the peer devices can be regarded as the
responders. More particularly, the initiator may uses the
pre-association broadcast (or multicast) request frame, such as a
probe request or a Generic Advertisement Service (GAS) request, as
a timing measurement request to solicit multiple responders to
directly perform timing measurement operations such as some
interactions for measuring the time of flight (or the time of
electromagnetic wave propagation) between the electronic device and
each of the responders whose locations are known. For example, each
of the responders may send a pre-association uni-cast response
frame, such as a probe response frame or a GAS response frame, as a
timing measurement frame. Regarding determining the location of the
electronic device in a situation where the locations of three
points in the wireless network system and the time of flight (or
the time of electromagnetic wave propagation) between the
electronic device and each of the three points are known, please
refer to Institute of Electrical and Electronics Engineers (IEEE)
802.11 standards (e.g. "IEEE 802.11-2012" standards) for more
information when needed.
[0018] As a result of using the pre-association broadcast request
frame to simultaneously trigger the responders to initiate the
timing measurement, the total number of exchange frames of multiple
peers can be reduced significantly in comparison with the related
art, where it is unnecessary to perform peer-to-peer IEEE 802.11v
timing measurement frame handshaking of the related art before the
feedback of the timing measurement report. In addition, the time
and power consumption of the additional discovery phase of the
related art and the information query phase of the related art can
be saved since all information required can be obtained during (or
before) the timing measurement process triggered by the
pre-association broadcast request frame. For example, the locations
of the three points can be carried by the aforementioned
pre-association uni-cast response frames, and therefore can be sent
to the electronic device right after the pre-association broadcast
request frame is sent. In another example, the locations of the
three points can be retrieved from the Internet or somewhere else
in the wireless network system in advance, rather than being sent
from the responders at this moment during the timing
measurement.
[0019] FIG. 2 illustrates a wireless network system 200 comprising
the aforementioned electronic device of the embodiment shown in
FIG. 1 according to an embodiment of the present invention, where
the wireless network system 200 can be taken as an example of the
aforementioned wireless network system in the embodiment shown in
FIG. 1. As shown in FIG. 2, the electronic device in this
embodiment (labeled "STA" in FIG. 2, where the notation "STA"
stands for "Station") may move from a point to another point since
the user of the electronic device may carry the electronic device
to walk around. For example, the user carrying the electronic
device may walk to the center of the region 205-1, and the
apparatus 100 may control the electronic device to send a single
request (labeled "Request" in FIG. 2) to start performing timing
measurement for location estimation corresponding to the center of
the region 205-1, and then some of the peer devices (labeled "AP"
in FIG. 2, where the notation "AP" stands for "Access Point") in
the wireless network system 200 is triggered to send responses to
the electronic device, respectively, where the notations "1" and
"2" labeled on the request and the responses illustrated within the
region 205-1 indicate that the request is sent first and then the
responses are sent. Similarly, the user carrying the electronic
device may walk to the center of the region 205-2, and the
apparatus 100 may control the electronic device to send a single
request to start performing timing measurement for location
estimation corresponding to the center of the region 205-2, in
order to update the location of the electronic device. Similarly,
the user carrying the electronic device may walk to the center of
the region 205-3, and the apparatus 100 may control the electronic
device to send a single request to start performing timing
measurement for location estimation corresponding to the center of
the region 205-3, in order to update the location of the electronic
device.
[0020] FIG. 3 illustrates a flowchart of a method 300 for
performing timing measurement for location estimation of an
electronic device according to an embodiment of the present
invention. The method shown in FIG. 3 can be applied to the
apparatus 100 shown in FIG. 1 (more particularly, the electronic
device STA of the embodiment shown in FIG. 2), and can be applied
to the processing circuit 110 thereof (more particularly, the
processing circuit 110 executing the program codes 110P of the
embodiment shown in FIG. 1). The method is described as
follows.
[0021] In Step 310, the processing circuit 110 sends, by utilizing
the transceiver 120, a pre-association broadcast request frame such
as that mentioned above to trigger multiple responders in a
wireless network system such as the wireless network system 200 to
initiate the timing measurement. For example, the pre-association
broadcast request frame can be a probe request frame. In another
example, the pre-association broadcast request frame can be a GAS
request frame.
[0022] In Step 320, the processing circuit 110 performs timing
measurement according to a plurality of timestamps, for determining
a location of the electronic device, where a portion of the
plurality of timestamps can be obtained from the responders, and
another portion of the plurality of timestamps can be determined
within the electronic device. For example, within the plurality of
timestamps, at least one timestamp can be determined based on a
pre-association uni-cast response frame received from one of the
responders, such as the pre-association uni-cast response frame
mentioned in the embodiment shown in FIG. 1. More particularly, no
actual association is established between the electronic device and
any of the responders.
[0023] According to this embodiment, for a specific responder of
the responders (e.g. the aforementioned one of the responders), a
first timestamp t1 and a second timestamp t2 within the plurality
of timestamps respectively correspond to a time of departure (ToD)
and a time of arrival (ToA) of a pre-association uni-cast response
frame received from the specific responder, and a third timestamp
t3 and a fourth timestamp t4 within the plurality of timestamps
respectively correspond to a ToD and a ToA of an acknowledgement
(or ACK) frame corresponding to this pre-association uni-cast
response frame, the acknowledgement frame sent from the electronic
device to the specific responder. For example, in a situation where
the pre-association broadcast request frame is a probe request
frame, this pre-association uni-cast response frame can be a probe
response frame. In another example, in a situation where the
pre-association broadcast request frame is a GAS request frame,
this pre-association uni-cast response frame can be a GAS response
frame.
[0024] More particularly, the aforementioned specific responder may
represent each responder of at least one portion (e.g. a portion or
all) of the responders. For example, the specific responder may
represent each responder of a portion of the responders. This is
for illustrative purposes only, and is not meant to be a limitation
of the present invention. In another example, the specific
responder may represent each of the responders.
[0025] According to some embodiments of the present invention, such
as some variations of the embodiment shown in FIG. 3, as updating
the location of the electronic device may be needed, the whole
working flow of the method 300 can be repeated. For example, after
the operations of Step 320 are completed, Step 310 can be
re-entered for updating the location of the electronic device.
[0026] FIG. 4 illustrates a control scheme involved with the method
300 shown in FIG. 3 according to an embodiment of the present
invention, where the electronic device (labeled "The initiator" in
FIG. 4, for better comprehension) may perform operations under
control of the processing circuit 110. For a specific responder
such as that mentioned above, the meanings of the timestamps {t1,
t2, t3, t4} can be the same as that of the embodiment shown in FIG.
3, where another set of timestamps {t1', t2', t3', t4'} may
represent the associated timestamps corresponding another responder
within the responders mentioned in Step 310 (more particularly, any
of the other responders within the responders mentioned in Step
310, i.e. any responder within the responders mentioned in Step 310
except for the specific responder mentioned above).
[0027] As shown in FIG. 4, the initiator, i.e. the electronic
device of this embodiment (more particularly, the processing
circuit 110 therein), uses a single request frame such as the
aforementioned pre-association broadcast request frame (e.g. a
probe request, or a GAS request) to trigger multiple responders to
initiate the timing measurement, where the time-measurement-related
operations of the responders are triggered by the same request
frame, and more particularly, can be triggered at the same time.
For example, the specific responder may send one of the uni-cast
response frames shown in FIG. 4, such as the pre-association
uni-cast response frame sent at the time represented by the
timestamp t1, to the initiator. Then, the initiator, i.e. the
electronic device of this embodiment (more particularly, the
processing circuit 110 therein), may send the corresponding
acknowledgement frame (labeled "ACK" in FIG. 4, for brevity) to the
specific responder. As the timestamps t1 and t4 can be obtained (or
captured) by the specific responder while the timestamps t2 and t3
can be obtained (or captured) by the initiator, the specific
responder may send a timing measurement report (labeled "TM report"
in FIG. 4, for brevity) such as a uni-cast report frame carrying
the timestamps t1 and t4 to the initiator, where the initiator may
send another acknowledgement frame (labeled "ACK" in FIG. 4, for
brevity) to acknowledge the reception of this timing measurement
report. Thus, the initiator, i.e. the electronic device of this
embodiment (more particularly, the processing circuit 110 therein),
can determine or estimate the time of flight (ToF) relative to the
specific responder sending this timing measurement report based on
the following equation:
ToF=((t4-t1)-(t3-t2))/2;
where the distance between the initiator and the specific responder
can be determined or estimated to be (c*ToF), with the notation "c"
representing the speed of light in vacuum. That is, the initiator,
i.e. the electronic device of this embodiment (more particularly,
the processing circuit 110 therein), can determine or estimate the
distance between the initiator and the specific responder based on
the following equation:
D=(c*ToF)=c*((t4-t1)-(t3-t2))/2;
where the notation "D" represents the distance between the
initiator and the specific responder. As a result, the distance D
between the electronic device and the specific responder can be
utilized for determining the location of the electronic device.
[0028] Please note that similar operations may be applied to the
interactions between the initiator and another responder such as
that mentioned above (more particularly, any of the other
responders within the responders mentioned in Step 310, i.e. any
responder within the responders mentioned in Step 310 except for
the specific responder mentioned above). In another example, the
other responder may send another one of the uni-cast response
frames shown in FIG. 4, such as the pre-association uni-cast
response frame sent at the time represented by the timestamp t1',
to the initiator. Then, the initiator, i.e. the electronic device
of this embodiment (more particularly, the processing circuit 110
therein), may send the corresponding acknowledgement frame (labeled
"ACK" in FIG. 4, for brevity) to the other responder. As the
timestamps t1' and t4' can be obtained (or captured) by the other
responder while the timestamps t2' and t3' can be obtained (or
captured) by the initiator, the other responder may send a timing
measurement report (labeled "TM report" in FIG. 4, for brevity)
such as a uni-cast report frame carrying the timestamps t1' and t4'
to the initiator, where the initiator may send another
acknowledgement frame (labeled "ACK" in FIG. 4, for brevity) to
acknowledge the reception of this timing measurement report. Thus,
the initiator, i.e. the electronic device of this embodiment (more
particularly, the processing circuit 110 therein), can determine or
estimate the time of flight (denoted ToF' for this example to
prevent confusion) relative to the other responder sending this
timing measurement report based on the following equation:
ToF'=((t4'-t1')-(t3'-t2'))/2;
where the distance between the initiator and the other responder
can be determined or estimated to be (c*ToF'), with the notation
"c" representing the speed of light in vacuum. That is, the
initiator, i.e. the electronic device of this embodiment (more
particularly, the processing circuit 110 therein), can determine or
estimate the distance between the initiator and the other responder
based on the following equation:
D'=(c*ToF')=c*((t4'-t1')-(t3'-t2'))/2;
where the notation "D'" represents the distance between the
initiator and the other responder. As a result, the distance D'
between the electronic device and the other responder can be
utilized for determining the location of the electronic device.
[0029] In general, the equations disclosed above can be
collectively expressed as follows:
ToF(n)=((t4(n)-t1(n))-(t3(n)-t2(n)))/2; and
D(n)=(c*ToF(n))=c*((t4(n)-t1(n))-(t3(n)-t2(n)))/2;
where the index n corresponds to the responder under consideration
within the responders, such as the responder R(n) (e.g. the
specific responder, or the other responder mentioned above). Thus,
the initiator and the responder R(n) are arranged to capture four
timestamps including ToDs and ToAs for a transmitted response frame
and the corresponding ACK frame, respectively, where the responder
R(n) uses a uni-cast report frame to provide its locally captured
timestamps to the initiator. As a result, the initiator can
determine or estimate a set of time of flight {ToF(n)} relative to
the aforementioned multiple responders using the plurality of
timestamps. In addition, the initiator can further determine or
estimate a set of distances {D(n)} between the initiator and the
responders {R(n)}, respectively, in order to determine the location
of the initiator, i.e. the location mentioned in Step 320. Please
note that the initiator may utilize a terminate frame (which is a
broadcast or multicast frame) to cancel the measurement process if
known points are enough to calculate the aforementioned location of
the electronic device.
[0030] Based on the method 300 shown in FIG. 3, and more
particularly, the control scheme shown in FIG. 4, the processing
circuit 110 can perform the aforementioned timing measurement
according to the plurality of timestamps, without need to establish
the association between the initiator (i.e. the electronic device)
and any of the responders {R(n)} first. For example, the processing
circuit 110 can perform the aforementioned timing measurement
according to the plurality of timestamps, without establishing the
association between the initiator (i.e. the electronic device) and
any of the responders {R(n)} in advance. In comparison with the
related art, the number of frame exchanges in the wireless network
system can be greatly reduced based on the embodiments disclosed
above.
[0031] Those skilled in the art will readily observe that numerous
modifications and alterations of the device and method may be made
while retaining the teachings of the invention. Accordingly, the
above disclosure should be construed as limited only by the metes
and bounds of the appended claims.
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