U.S. patent application number 14/094956 was filed with the patent office on 2015-06-04 for methods and devices for path-loss estimation.
This patent application is currently assigned to Motorola Mobility LLC. The applicant listed for this patent is Motorola Mobility LLC. Invention is credited to Mark R. Braun, Scott P. Debates, Francis W. Forest, James A. Van Bosch.
Application Number | 20150156647 14/094956 |
Document ID | / |
Family ID | 52273496 |
Filed Date | 2015-06-04 |
United States Patent
Application |
20150156647 |
Kind Code |
A1 |
Braun; Mark R. ; et
al. |
June 4, 2015 |
Methods and Devices for Path-Loss Estimation
Abstract
A method on an electronic device for a wireless network is
described. A wireless signal is received from a second electronic
device. A receive power level indication for the received wireless
signal is determined. A path-loss offset for the received wireless
signal is determined based on sensor data that indicates a
path-loss condition. A path-loss for the received wireless signal
is estimated based on the receive power level indication and the
path-loss offset. A function is performed based on the path-loss
and the path-loss threshold.
Inventors: |
Braun; Mark R.; (Elgin,
IL) ; Debates; Scott P.; (Crystal Lake, IL) ;
Forest; Francis W.; (Lake Villa, IL) ; Van Bosch;
James A.; (Crystal Lake, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Motorola Mobility LLC |
Libertyville |
IL |
US |
|
|
Assignee: |
Motorola Mobility LLC
Libertyville
IL
|
Family ID: |
52273496 |
Appl. No.: |
14/094956 |
Filed: |
December 3, 2013 |
Current U.S.
Class: |
455/426.1 ;
455/552.1 |
Current CPC
Class: |
H04W 64/00 20130101;
H04W 52/242 20130101; H04W 24/08 20130101; H04W 4/80 20180201; H04W
88/06 20130101; H04W 52/14 20130101; H04W 76/10 20180201; H04B
17/318 20150115; H04B 17/27 20150115 |
International
Class: |
H04W 24/08 20060101
H04W024/08; H04W 76/02 20060101 H04W076/02; H04W 4/00 20060101
H04W004/00 |
Claims
1. A method in a first electronic device, the method comprising:
receiving a wireless signal from a second electronic device;
determining a receive power level indication for the received
wireless signal; determining a path-loss offset for the received
wireless signal based on sensor data that indicates a path-loss
condition; estimating a path-loss for the received wireless signal
based on the receive power level indication and the path-loss
offset; performing a function based on the path-loss and the
path-loss threshold.
2. The method of claim 1 further comprising: determining a transmit
power level indication for the second electronic device; wherein
estimating the path-loss for the received wireless signal comprises
offsetting a difference between the transmit power level indication
and the receive power level indication with the path-loss offset to
determine the path-loss.
3. The method of claim 1 further comprising receiving at least a
portion of the sensor data from the second electronic device.
4. The method of claim 3 further comprising: selecting a context
update interval based on the sensor data; polling the second device
for the portion of the sensor data at the context update
interval.
5. The method of claim 3 further comprising: selecting a context
update interval based on the sensor data; setting an advertising
interval of the second device to the context update interval.
receiving the portion of the sensor data from the second electronic
device at the context update interval.
6. The method of claim 3 wherein receiving the portion of the
sensor data comprises: sending an indication of sensor data to the
second electronic device; receiving the portion of the sensor data
in response to the indication of the sensor data.
7. The method of claim 1 wherein determining the path-loss offset
comprises: determining that the sensor data indicates a movement
type for at least one of the first electronic device or the second
electronic device; selecting the path-loss offset based on the
movement type.
8. The method of claim 1 wherein determining the path-loss offset
comprises: determining that the sensor data indicates a device
context indicator for at least one of the first electronic device
or the second electronic device, wherein the device context
indicator affects the receive power level indication; selecting the
path-loss offset based on the device context indicator.
9. The method of claim 8 wherein the sensor data indicates at least
one of a stowing status, proximity to a face, handheld status,
surface positioning, device heading, microphone input, ambient
light sensor data, barometric pressure, ambient temperature, global
positioning system data, Wi-Fi connection data, Bluetooth.TM.
connection data, Zigbee connection data, accelerometer data,
gyroscope data, capacitive sensor data, or location.
10. The method of claim 8 wherein determining that the sensor data
indicates the device context indicator comprises determining that
the sensor data indicates a plurality of device context indicators
that affect the receive power level indication; wherein selecting
the path-loss offset based on the device context indicator
comprises: selecting a condition offset for each of the plurality
of device context indicators; combining the condition offsets for
the plurality of device context indicators to obtain the path-loss
offset.
11. The method of claim 1 wherein determining the receive power
level indication comprises: performing a procedure on a plurality
of receive power level indications over a receive power average
interval to determine the receive power level indication;
dynamically adjusting the receive power average interval based on
the sensor data.
12. The method of claim 1 wherein determining the receive power
level indication comprises: determining a plurality of receive
power level indications; selecting one or more procedures based on
at least one of the sensor data or a device context indicator;
performing the one or more procedures on at least one receive power
level indication of the plurality of receive power level
indications to determine the receive power level indication.
13. The method of claim 1 wherein performing the function comprises
triggering at least one of an alert function, a security function,
or a proximity-triggered function.
14. A first electronic device comprising: a radio transceiver; a
non-transitory memory; and a processor configured to retrieve
instructions from the memory; wherein: the radio transceiver is
configured to receive a wireless signal from a second electronic
device; the radio transceiver is configured to determine a receive
power level indication for the received wireless signal; the
processor is configured to determine a path-loss offset for the
received wireless signal based on sensor data that indicates a
path-loss condition; the processor is configured to estimate a
path-loss for the received wireless signal based on the receive
power level indication and the path-loss offset; and the processor
is configured to perform a function based on the path-loss and the
path-loss threshold.
15. The first electronic device of claim 14 wherein the second
electronic device is a smart watch, key fob, smart pen, pair of
smart glasses, tablet computer, audio headset, or a wearable
electronic device.
16. The first electronic device of claim 14 wherein the first
electronic device is a tablet computer.
17. The first electronic device of claim 14 wherein the first
electronic device is a cellular telephone.
18. A method in a first electronic device, the method comprising:
negotiating a wireless communication connection with a second
electronic device; determining whether at least one of the first
electronic device or the second electronic device is located
outdoors based on sensor data; selecting a wireless communication
channel for the wireless communication connection based on the
determination; establishing the wireless communication connection
with the second electronic device over the selected wireless
communication channel.
19. The method of claim 18 wherein selecting the wireless
communication channel comprises: selecting the wireless
communication channel from a first set of wireless communication
channels for outdoor use if the first electronic device or the
second electronic device is located outdoors; selecting the
wireless communication channel from a second set of wireless
communication channels for indoor use if both the first electronic
device and the second electronic device are not located
outdoors.
20. The method of claim 19 further comprising: receiving a wireless
signal from the second electronic device over the selected wireless
communication channel; determining a receive power level indication
for the received wireless signal; determining a path-loss offset
for the received wireless signal based on the sensor data, wherein
the sensor data indicates a path-loss condition; estimating a
path-loss for the received wireless signal based on the receive
power level indication and the path-loss offset; performing a
function based on the path-loss and the path-loss threshold.
21. The method of claim 20 wherein determining the path-loss offset
comprises: determining that the sensor data indicates a device
context indicator for at least one of the first electronic device
or the second electronic device, wherein the device context
indicator affects the receive power level indication; selecting the
path-loss offset based on the device context indicator.
22. The method of claim 21 wherein the sensor data indicates at
least one of a stowing status, proximity to a face, handheld
status, surface positioning, device heading, microphone input,
ambient light sensor data, barometric pressure, ambient
temperature, global positioning system data, Wi-Fi connection data,
Bluetooth.TM. connection data, Zigbee connection data,
accelerometer data, gyroscope data, capacitive sensor data, or
location.
23. The method of claim 20 wherein determining the path-loss offset
comprises: selecting the path-loss offset based on the
determination of whether at least one of the first electronic
device or the second electronic device is located outdoors.
Description
[0001] TECHNICAL FIELD
[0002] The present disclosure is related generally to wireless
device communication and, more particularly, to estimation of
path-loss between wireless devices.
BACKGROUND
[0003] Electronic devices, such as smartphones and tablets are
often used in combination with wearable electronic devices, such as
wireless headsets or watches. For example, a user may have a
smartphone and a smart watch that are communicatively linked or
"paired" to each other via Bluetooth.TM. or other wireless
communication technologies. A wireless communication link between
the smartphone and watch allows for exchanging data between them,
but also for estimating their proximity. The smartphone (or watch)
may be configured to alert the user when the distance to the paired
device reaches a predetermined threshold to prevent the user from
leaving the paired device behind, prevent moving the device without
the user's knowledge (e.g., being stolen), or to lock either device
to prevent unauthorized access when out of range.
[0004] The smartphone may estimate a distance between itself and
the watch based on a signal strength of a wireless signal received
from the watch; however, various factors affect the received signal
strength independently from the actual distance. Environmental
factors, such as moving between rooms in a house or office
building, can increase interference and reduce the received signal
strength as the wireless signal must travel through walls and other
materials. Moving from an indoor location to an outdoor location
can also reduce received signal strength due to fewer multipath
signal reflections. Variations in received signal strength caused
by environmental factors can cause the smartphone to alert the
user, based on the received signal strength, when the actual
distance between the smartphone and the watch is within an
acceptable range.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0005] While the appended claims set forth the features of the
present techniques with particularity, these techniques, together
with their objects and advantages, may be best understood from the
following detailed description taken in conjunction with the
accompanying drawings of which:
[0006] FIG. 1 is an overview of a representative communication
system in which the methods of this disclosure may be
practiced;
[0007] FIG. 2 is a simplified block diagram of a representative
electronic device.
[0008] FIG. 3 is a simplified block diagram of another
implementation of the electronic device with a remote device;
[0009] FIG. 4 is a process flow of a method for estimation of a
path-loss between the electronic device and the remote device of
FIG. 3;
[0010] FIG. 5 is a process flow of a method for determining a
device context indicator that may be performed by the electronic
device of FIG. 3;
[0011] FIG. 6 is a process flow of a method for establishing a
wireless communication connection between the electronic device and
the remote device of FIG. 3.
DETAILED DESCRIPTION
[0012] Turning to the drawings, wherein like reference numerals
refer to like elements, the following description is based on
embodiments of the claims and should not be taken as limiting the
claims with regard to alternative embodiments that are not
explicitly described herein.
[0013] The various embodiments described herein allow a smartphone
or other electronic device to improve accuracy of
proximity-triggered functions by using sensor data that indicates a
path-loss condition. When a path-loss condition is determined, a
path-loss offset is determined and used for estimation of the
path-loss. The path-loss offset compensates for the path-loss
condition to reduce false proximity alerts. As one example, a
smartphone may be configured with a proximity-triggered function
such as an alarm that activates when a smart watch is further than
1.0 meters away. When both the smartphone and watch are located
indoors, the smartphone may use a received signal strength
corresponding to the smart watch to determine its proximity as a
first value, such as 0.75 meters when the phone is set nearby on a
table. The received signal strength is affected by environmental
conditions such as multi-path reception or interference due to
obstructions. Moving the smartphone and watch outdoors may reduce
the effect of multi-path reception, resulting in a lower received
signal strength. For example, the lower received signal strength
may correspond to a distance of 1.2 meters even when the actual
distance between the smartphone and smart watch has remained the
same (i.e., 0.75 meters). Accordingly, the smartphone is configured
to determine a path-loss offset to compensate for the reduced
multi-path reception (or other path-loss condition), thus reducing
the occurrence of a false proximity alert. The smartphone
determines the path-loss offset based on sensor data that indicates
whether the smartphone or smart watch is indoors or outdoors,
stowed in a pocket or bag, or placement in the user's hand. Other
path-loss conditions and corresponding sensor data will be apparent
to those skilled in the art.
[0014] In one embodiment, an electronic device determines a
path-loss offset based on sensor data that indicates a path-loss
condition. The electronic device estimates a path-loss based on the
path-loss offset and a received signal strength from another
electronic device. The electronic device then performs a function
based on the estimated path-loss.
[0015] Turning to FIG. 1, a pair of electronic devices 110 and 120
is shown. Possible implementations of the electronic devices 110
and 120 include a smartphone, tablet, wireless wristwatch (e.g., a
"smart watch"), wireless headset, laptop or personal computer, key
fob, wireless-enabled glasses, smart pen, or other wireless
communication enabled device. As shown in the example of FIG. 1,
the electronic device 110 is a smartphone and the electronic device
120 is a wireless headset of a user 125. One or more of the
electronic devices 110 or 120 may be configured to receive
communications from a satellite-based positioning system 150 or a
wireless network 160. Examples of the satellite-based positioning
system 150 include the global positioning system ("GPS"),
Globalnaya Navigatsionnaya Sputnikovaya Sistema ("GLONASS"), BeiDou
Navigation Satellite System, Galileo navigation system, and Indian
Regional Navigational Satellite System. Possible implementations of
the wireless network 160 include a cellular network, Institute of
Electrical and Electronics Engineers ("IEEE") 802.11 network, or
other wireless communication network.
[0016] Turning to FIG. 2, a simplified block diagram illustrates an
embodiment of an electronic device 200. The electronic device 200
in one example implements one or more of the electronic devices 110
or 120. As shown in FIG. 2, the electronic device 200 includes a
processor 202 that executes stored programs. The electronic device
200 further includes a memory 204. The processor 202 writes data to
and reads data from the memory 204. The electronic device 200 also
includes a radio transceiver 206 and antenna 207 configured for
sending and receiving data, for example, over a wireless network
(e.g., the wireless network 160 of FIG. 1) or with other electronic
devices (e.g., via a wireless communication link). In a further
example, the radio transceiver 206 and antenna 207 are configured
for receiving communications from a satellite-based positioning
system (e.g., the satellite-based positioning system 150 of FIG.
1). In some embodiments, the electronic device 200 has a user input
interface 208 that may include one or more of a keypad, display
screen, touch screen, or the like. In some embodiments, the
electronic device 200 includes one or more sensors 210. Possible
implementations of the sensors 210 include a gyroscope,
accelerometer, magnetometer, ambient light sensor, temperature
sensor, microphone, barometer, or proximity sensor. In alternative
implementations, various components of the electronic device 200
may be combined or divided. For example, the radio transceiver 206
or antenna 207 may be separated into a plurality of components for
separately handling GPS, Bluetooth.TM., 802.11, and cellular
communications. Alternatively, the radio transceiver 206 may be
configured as a combined radio transceiver for multiple wireless
communication protocols or links
[0017] Referring again to FIG. 1, the electronic devices 110 and
120 are configured to establish a wireless communication link 130
between each other. Possible implementations of the wireless
communication link 130 include a Bluetooth.TM. link, IEEE 802.11
link, IEEE 802.15 link, or other radio frequency ("RF")
communication link. For a Bluetooth.TM. link, the electronic
devices 110 and 120 may implement the Proximity Profile as defined
in Bluetooth.TM. Specification PXP_SPEC (available from
https://www.bluetooth.org/en-us/specification/adopted-specifications-
). In this case, the electronic device 110 implements the proximity
monitor role while the electronic device 120 implements the
proximity reporter role. In other examples, the roles are reversed
between the electronic devices 110 and 120 or additional roles may
be implemented.
[0018] To aid in the clarity of the description, each device will
be referred to by the role that it plays with respect to a
Bluetooth.TM. implementation while carrying out the methods set
forth in this disclosure. More specifically, the first device will
be referred to as the monitoring device 110 (e.g., a smartphone)
while the second device will be referred to as the reporting device
120 (e.g., a headset). In practice, however, either device could
act as a monitoring device or as a reporting device. In other
words, the generic term "first device" can refer to either a
monitoring device or a reporting device. Likewise, the generic term
"second device" can refer to either a monitoring device or a
reporting device. Additionally, the methods may be practiced with
other RF communication technologies.
[0019] The monitoring device 110 is configured to estimate
path-loss on the wireless communication link 130 with the reporting
device 120 based on a received signal strength associated with the
reporting device 120 and a path-loss offset. For example, the
monitoring device 110 calculates a first path-loss by subtracting a
received signal strength (e.g., RSSI) from a transmit signal
strength (e.g., a TX power level indication). The monitoring device
110 determines a transmit power level indication for the reporting
device 120 based on a TX power message received from the reporting
device 120. Based on the calculated first path-loss, the monitoring
device 110 estimates a second path-loss (i.e., an estimated second
path-loss) by adding the path-loss offset to the calculated first
path-loss. The monitoring device 110 is configured to determine the
path-loss offset based on sensor data from the sensors 210. The
monitoring device 110 then estimates the second path-loss on the
wireless communication link 130 using the received signal strength
and path-loss offset.
[0020] For determination of the path-loss offset, the monitoring
device 110 in one example determines a device context indicator
based on an output from one or more sensors (e.g., sensors 210 of
FIG. 2), data received from a remote device (e.g., via radio
transceiver 206 of FIG. 2), or data stored in the monitoring device
110. The device context indicator may be a raw signal output from a
sensor or a processed output from a single sensor or multiple
sensors. Examples of the device context indicator include a current
location of the monitoring device 110, a movement speed or movement
type associated with the monitoring device 110, a movement
velocity, an orientation or surface positioning of the monitoring
device 110, a state indicator for the monitoring device 110 (e.g.,
a user interface setting or lock status), a connection status with
another device (e.g., Bluetooth.TM., Wi-Fi, Zigbee), sensor data of
the monitoring device 110, a device heading, microphone input,
ambient light sensor data, capacitive sensor data, detection status
or path-loss for another device (not shown) or a stationary
wireless network 160, or a received signal strength of a stationary
wireless network 160. In another example, the device context
indicator is a status indicator that indicates an activity or
movement type in which the user 125 is engaged, such as driving,
walking, running, or bicycling. The state indicator for the
monitoring device 110 in one example indicates whether the
monitoring device 110 or reporting device 120 is stowed (e.g., in a
pocket or bag).
[0021] In a further example, the monitoring device 110 receives
sensor data or one or more device context indicators from the
reporting device 120 (e.g., via the wireless communication link
130). The device context indicators from the reporting device 120
may be the same or different (e.g., movement speed of the reporting
device 120, orientation of the reporting device 120, received
signal strength, etc.). Accordingly, the monitoring device 110 may
use device context indicators or sensor data from both the
monitoring device 110 and the reporting device 120 to determine the
path-loss offset. In yet another example, the monitoring device 110
obtains a device context indicator from another remote electronic
device (e.g., via the wireless network 160 or another wireless
communication link). Accordingly, the device context indicator may
be associated with the monitoring device 110, the reporting device
120, or another device (not shown).
[0022] One example of a device context indicator is a movement
type, such as whether the device is stationary or moving. In some
implementations, the movement type is more specific, such as
motionless, micromotion, walking, running, driving or movement in a
vehicle, arm swinging, arm steering a car, pen writing, or others.
In one example, the monitoring device 110 determines that the user
125 is driving based on a movement speed and a location obtained
based on signals from the satellite-based positioning system 150
(e.g., moving above 40 miles per hour and located on an
expressway). In this case, the monitoring device 110 selects a
path-loss offset that corresponds to path-loss within a vehicle.
The monitoring device 110 in one example determines a path-loss
offset that compensates for signal fade due to movement speed or
type.
[0023] In yet another example, the monitoring device 110 may
determine the location, movement speed, movement velocity, or
movement type based on detection of or proximity to a stationary
Wi-Fi network (e.g., based on received signal strength or a change
in received signal strength) such as the wireless network 160
(e.g., a fixed Wi-Fi network located at the user's home or place of
work).
[0024] Turning to FIG. 3, another implementation of the monitoring
device 200 of FIG. 2 is shown with a reporting device 301. The
monitoring device 200 in this implementation further includes a
context component 302 for determination of the device context
indicators. The monitoring device 200 further includes a path-loss
component 304 for determination of the path-loss offset based on
the sensor data or device context indicators and estimation of the
path-loss. The monitoring device 200 includes a plurality of
sensors 210, such as a positioning sensor 311 (e.g., for GPS
positioning or RF triangulation), gyroscope 312, accelerometer 313,
proximity sensor 314, temperature sensor 315, barometric sensor
316, and magnetometer 318. The monitoring device 200 may have
additional or fewer sensors 210 in alternative embodiments. The
reporting device 301 includes a sensor 322. The context component
302 is configured to receive sensor data from the sensors 210 and
also from the sensor 322 (via the radio transceiver 206).
[0025] Turning to FIG. 4, a process flow 400 illustrates one
example of a method performed by the monitoring device 110,
according to an embodiment. The monitoring device 110 starts the
process flow 400 upon a predetermined schedule or interval, such as
a context update interval (e.g., every 200 milliseconds, every
second, every three seconds, or other intervals). In another
implementation, the monitoring device 110 starts the process flow
400 in response to a signal or message. The signal or message in
one example indicates a change in an RF measurement or sensor data.
For example, a sudden drop in a Wi-Fi signal may indicate that the
user 125 has left a predetermined location (e.g., the user's home)
or another fixed location. Alternatively, a sudden drop in a GPS
signal may indicate that the user has gone indoors.
[0026] The monitoring device 110 determines (402) sensor data at
the context update interval. As described above, the sensor data
(or portions thereof) may be received from the sensors 210 of the
monitoring device 110 or received from the reporting device 120.
Where the sensor data is from the reporting device 120, the
monitoring device 110 may poll the reporting device 120 at the
context update interval or alternatively, set an advertising
interval of the reporting device 120 to be the context update
interval. When using the advertising interval, the monitoring
device 110 may send an indication of which sensor data of the
reporting device 120 should be sent by the reporting device 120.
Optionally, the monitoring device 110 analyzes the sensor data to
determine a device context indicator for the monitoring device 110
or the reporting device 120 as described herein with reference to
FIG. 5.
[0027] The monitoring device determines (404) the path-loss offset
and the context update interval based on the sensor data or device
context indicators. The monitoring device 110 in one example uses a
lookup table or database with sensor data values or device context
indicators that correspond to path-loss offsets. The lookup table
or database may be created based on empirical measurements of
path-loss under various conditions or interpolation of
measurements, as will be apparent to those skilled in the art. In
another example, the monitoring device 110 dynamically determines
the path-loss offset using an algorithm or procedure that is
performed on the sensor data.
[0028] In alternative implementations, the monitoring device 110
may determine whether the path-loss offset or context update
interval should be changed based on the sensor data or device
context indicators. For example, where several device context
indicators have changed or are inconsistent with each other, one or
more of the changes or device context indicators may cancel another
out. In this case, the monitoring device 110 combines corresponding
path-loss offsets for the device context indicators (e.g.,
condition offsets) or proceeds without updating the path-loss
offset. As one example, outputs from the magnetometer 318 and the
gyroscope 312 may be compared for consistency (e.g., based on
angular momentum in the case of a mechanical gyroscope) to reduce
an effect of inaccuracies in the magnetometer 318 due to a magnetic
anomaly. In this case, a path-loss offset based on the magnetometer
318 may be ignored as inconsistent with the gyroscope 312. The
context update interval may also be combined or averaged based on
the sensor data. The monitoring device 110 in one example adjusts
the context update interval to reduce battery drain on the
monitoring device 110 or reporting device 120.
[0029] The monitoring device 110 in one example determines (406) a
receive power average interval based on the sensor data or device
context indicators. The receive power average interval is used for
determination of the received signal strength, as described herein.
The monitoring device 110 receives (408) at least one wireless
signal over the wireless communication link 130 from the reporting
device 120. The received wireless signal may be a wireless signal
requested by the monitoring device 110 for purposes of determining
the path-loss or a wireless signal sent for another purpose, such
as a data transfer.
[0030] The monitoring device 110 determines (410) a received signal
strength based on the received wireless signal (or multiple
wireless signals). The received signal strength in one example is a
received signal strength indicator ("RSSI") or received channel
power indicator ("RCPI"). The monitoring device 110 estimates (412)
the path-loss based on the path-loss offset. The estimation is
performed on the occurrence of the receive power average interval.
For example, the monitoring device 110 estimates the path-loss
repeatedly at the receive power average interval, e.g., every 200
milliseconds, every second, every three seconds, or other
intervals. The monitoring device 110 in one example dynamically
determines the receive power average interval based on the sensor
data. The monitoring device 110 selects a relatively longer receive
power average interval (e.g., four seconds) when the sensor data
indicates that the monitoring device 110 or reporting device 120 is
stationary than when in motion (e.g., one second).
[0031] When estimating (412) the path-loss, the monitoring device
110 in one example performs one or more procedures on a plurality
of received signal strength indicators received over the receive
power average interval, or a subset thereof, to determine the
received signal strength. The monitoring device 100 may select the
one or more procedures to be applied to the received RSSI values
based on sensor data, device context indicators (e.g., whether the
monitoring device 110 is in motion or stationary), or a combination
thereof. Examples of procedures include an averaging filter, a
feedback filter, a finite impulse response ("FIR") filter, or
Viterbi algorithm. An averaging filter calculates the average RSSI
value from incoming received packets from the reporting device 120.
A feedback filter uses a portion of a most recent RSSI value for
each calculation and thus allows for smoothing of large difference
in RSSI values. The monitoring device 110 in one example selects
the feedback filter when stationary to reduce false triggering. In
another example, the monitoring device 110 selects the Viterbi
algorithm when the received RSSI values are rapidly changing (e.g.,
due to movement of the monitoring device 110).
[0032] The monitoring device 110 in one example estimates (412) the
path-loss as the path-loss offset added to a calculated path-loss.
The monitoring device 110 calculates a first path-loss as the
transmit power (e.g., a TX value) of the reporting device 120 minus
the received signal strength (e.g., RSSI). An indication of the
transmit power is received from the reporting device 120 (e.g.,
through a TX power message). In other implementations, the transmit
power may be a predetermined value, such as 0 dBm or +10 dBm. Where
the transmit power is zero, a magnitude of the calculated first
path-loss is equal to the RSSI. For example, a transmit power of 0
dBm and a received signal strength of -60 dBm results in a
calculated path-loss of 60 dBm. Based on the calculated first
path-loss, the monitoring device 110 estimates a second path-loss
(i.e., an estimated second path-loss) by adding the path-loss
offset to the calculated first path-loss. After estimation (412) of
the path-loss, the monitoring device 110 may optionally estimate
the distance to the reporting device 120, for example, using a
distance formula based on the estimated path-loss or a lookup
table. While received signal strength is described herein as units
of dBm, in alternative embodiments another measurement, metric, or
indicator may be used. For example, the received signal strength
may be indicated in dBW or a unitless value, such as a range of 0
to 100, 0 to 127, or others, as may be appreciated by those skilled
in the art.
[0033] While the steps of determining (402, 404, 406, 410), receipt
(408), and estimating (412) are shown as adjacent steps, the steps
may be performed as part of one or more separate process flows. In
this case, the monitoring device 110 may update the sensor data
multiple times before using the sensor data to determine the device
context indicators or estimate the path-loss. The context update
interval and the receive power average interval may be the same or
different. Thus, the monitoring device 110 may obtain the sensor
data every ten seconds while estimating the path-loss every
second.
[0034] Upon estimation (412) of the path-loss, the monitoring
device 110 in one example determines (414) whether the path-loss
meets an alert threshold. The alert threshold in one example is a
path-loss threshold value that indicates that a proximity-triggered
function should be performed. The monitoring device 110 uses a
path-loss threshold value that corresponds to a distance between
the monitoring device 110 and the reporting device 120. When using
the path-loss threshold value, the monitoring device 110 selects
the path-loss threshold value based on the sensor data or the
proximity-triggered function to be performed. Alternatively, the
path-loss threshold value may be predetermined. In other
implementations, the monitoring device 110 uses the estimated
distance based on the estimated path-loss to determine whether the
alert threshold has been met. In this case, the alert threshold is
a distance threshold, such as 1 meter, 4 meters, or other
distance.
[0035] Examples of the proximity-triggered function include locking
one or both of the monitoring device 110 and reporting device 120,
initiating an alert (e.g., an audible or visible notification) on
one or both devices, or sending a message to the reporting device
120 or to another device (not shown). The monitoring device 110
triggers or executes a proximity-triggered function when the
path-loss has met (e.g., become equal to or greater than) the
path-loss threshold value. For example, a user of the monitoring
device 110 may wish to be notified when the reporting device 120,
worn by the user's child, has moved (or been moved) 5 meters away
or farther from the monitoring device 110. In alternative
implementations, the monitoring device 110 may trigger the
proximity-triggered function when the path-loss has become less
than the path-loss threshold value.
[0036] The monitoring device 110 may use multiple alert thresholds
(path-loss threshold values, distance threshold values, or
combination thereof) corresponding to one or more
proximity-triggered functions. If the alert threshold is not met
(NO at 414), the process flow 300 ends (e.g., until the next
context update interval). If the alert threshold is met (YES at
414), the monitoring device 110 performs (416) the
proximity-triggered function and the process flow 400 ends.
[0037] Turning to FIG. 5, a process flow 500 illustrates one
example of a method performed by the monitoring device 110 for
determination of one or more device context indicators. In other
implementations, the process flow 500 may be performed by the
reporting device 120. As described above, the process flow 500 may
be performed at the context update interval or upon a change in
sensor data. The monitoring device 110 determines (502) a movement
status of the monitoring device 110, the reporting device 120, or
both devices. As one example, the monitoring device 110 determines
the movement status based on sensor data from the positioning
sensor 311, gyroscope 312, accelerometer 313, or magnetometer 318.
For example, if the monitoring device 110 detects periodic motion
from the accelerometer 313 that is consistent with walking, the
monitoring device 110 may determine that the device context
indicator for the movement type is "walking." As described above,
the monitoring device 110 determines a path-loss offset that
compensates for signal fade due to movement speed or type. For
example, if the reporting device 120 is a smart watch on the user's
wrist while the user is jogging, the reporting device 120 may
quickly move back and forth relative to the monitoring device 110.
The monitoring device 110 determines a path-loss offset that
corresponds to the movement of the reporting device 120.
[0038] The monitoring device 110 determines (504) a location status
of the monitoring device 110, the reporting device 120, or both
devices. The monitoring device 110 may determine that the user is
located in their home, at work, in a shopping mall, or at a park
based on the location from the satellite-based positioning system
150. In this case, the monitoring device 110 selects a path-loss
offset that corresponds to path-loss in the respective location.
The path-loss offset for the user's home (i.e., indoors) may be
lower than that in an open park (i.e., outdoors) due to multi-path
reception. In another example, the path-loss offset in a forest
preserve or heavily wooded area may be higher than the open park
due to signal interference from trees.
[0039] The monitoring device 110 determines (506) an environmental
status of the monitoring device 110, the reporting device 120, or
both devices. Examples of the environmental status include sensor
data from the temperature sensor 315 and barometer 316. The
monitoring device 110 in one example uses temperature and
atmospheric pressure data to determine whether the monitoring
device 110 is indoors or outdoors.
[0040] The monitoring device 110 determines (508) a stowing status
of the monitoring device 110, the reporting device 120, or both
devices. The monitoring device 110 in one example uses the
proximity sensor 314 or an ambient light sensor (not shown) to
determine whether the monitoring device is inside a bag or other
container. In this case, the monitoring device 110 may select a
path-loss offset to compensate for being inside of an enclosure as
opposed to having line of sight to the reporting device 120. The
monitoring device 110 may also use the proximity sensor 314 to
determine whether the device is currently being gripped or held
against the user's face (e.g., during a phone call). The monitoring
device 110 selects a larger path-loss offset if either device is
stowed or being held in order to compensate for interference due to
the container or user's body.
[0041] Turning to FIG. 6, a process flow 600 illustrates one
example of a method performed by the monitoring device 110 is shown
for establishing a wireless communication connection, such as the
wireless communication link 130. The monitoring device 110
negotiates (602) with the reporting device 120 as part of a pairing
process. For example, the monitoring device 110 and reporting
device 120 share their connection capabilities (e.g., frequencies,
protocols, or features). The monitoring device 110 determines (604)
whether it is located in an indoor or outdoor location. As
described above, the monitoring device 110 uses the sensor data or
device context indicators to determine the location. The monitoring
device 110 selects (606) a wireless communication channel for the
wireless communication connection based on the location
determination. For example, some wireless communication channels
within a set of channels may be restricted to indoor use only or
may have less interference when outdoors. Upon selection of the
wireless communication channel, the monitoring device 110
establishes (608) the wireless communication connection with the
reporting device 120 using the selected channel. The monitoring
device 110 may then estimate path-loss using the selected channel,
as described above with reference to FIG. 4.
[0042] It can be seen from the foregoing that a method and system
for improved accuracy of path-loss estimation is provided. In view
of the many possible embodiments to which the principles of the
present discussion may be applied, it should be recognized that the
embodiments described herein with respect to the drawing figures
are meant to be illustrative only and should not be taken as
limiting the scope of the claims. Therefore, the techniques as
described herein contemplate all such embodiments as may come
within the scope of the following claims and equivalents
thereof.
[0043] The apparatus described herein may include a processor, a
memory for storing program data to be executed by the processor, a
permanent storage such as a disk drive, a communications port for
handling communications with external devices, and user interface
devices, including a display, touch panel, keys, buttons, etc. When
software modules are involved, these software modules may be stored
as program instructions or computer readable code executable by the
processor on a non-transitory computer-readable media such as
magnetic storage media (e.g., magnetic tapes, hard disks, floppy
disks), optical recording media (e.g., CD-ROMs, Digital Versatile
Discs (DVDs), etc.), and solid state memory (e.g., random-access
memory (RAM), read-only memory (ROM), static random-access memory
(SRAM), electrically erasable programmable read-only memory
(EEPROM), flash memory, thumb drives, etc.). The computer readable
recording media may also be distributed over network coupled
computer systems so that the computer readable code is stored and
executed in a distributed fashion. This computer readable recording
media may be read by the computer, stored in the memory, and
executed by the processor.
[0044] The disclosed embodiments may be described in terms of
functional block components and various processing steps. Such
functional blocks may be realized by any number of hardware and/or
software components configured to perform the specified functions.
For example, the disclosed embodiments may employ various
integrated circuit components, e.g., memory elements, processing
elements, logic elements, look-up tables, and the like, which may
carry out a variety of functions under the control of one or more
microprocessors or other control devices. Similarly, where the
elements of the disclosed embodiments are implemented using
software programming or software elements, the disclosed
embodiments may be implemented with any programming or scripting
language such as C, C++, JAVA.RTM., assembler, or the like, with
the various algorithms being implemented with any combination of
data structures, objects, processes, routines or other programming
elements. Functional aspects may be implemented in algorithms that
execute on one or more processors. Furthermore, the disclosed
embodiments may employ any number of conventional techniques for
electronics configuration, signal processing and/or control, data
processing and the like. Finally, the steps of all methods
described herein may be performed in any suitable order unless
otherwise indicated herein or otherwise clearly contradicted by
context.
[0045] For the sake of brevity, conventional electronics, control
systems, software development and other functional aspects of the
systems (and components of the individual operating components of
the systems) may not be described in detail. Furthermore, the
connecting lines, or connectors shown in the various figures
presented are intended to represent exemplary functional
relationships and/or physical or logical couplings between the
various elements. It should be noted that many alternative or
additional functional relationships, physical connections or
logical connections may be present in a practical device. The words
"mechanism", "element", "unit", "structure", "means", "device",
"controller", and "construction" are used broadly and are not
limited to mechanical or physical embodiments, but may include
software routines in conjunction with processors, etc.
[0046] No item or component is essential to the practice of the
disclosed embodiments unless the element is specifically described
as "essential" or "critical". It will also be recognized that the
terms "comprises," "comprising," "includes," "including," "has,"
and "having," as used herein, are specifically intended to be read
as open-ended terms of art. The use of the terms "a" and "an" and
"the" and similar referents in the context of describing the
disclosed embodiments (especially in the context of the following
claims) are to be construed to cover both the singular and the
plural, unless the context clearly indicates otherwise. In
addition, it should be understood that although the terms "first,"
"second," etc. may be used herein to describe various elements,
these elements should not be limited by these terms, which are only
used to distinguish one element from another. Furthermore,
recitation of ranges of values herein are merely intended to serve
as a shorthand method of referring individually to each separate
value falling within the range, unless otherwise indicated herein,
and each separate value is incorporated into the specification as
if it were individually recited herein.
[0047] The use of any and all examples, or exemplary language
(e.g., "such as") provided herein, is intended merely to better
illuminate the disclosed embodiments and does not pose a limitation
on the scope of the disclosed embodiments unless otherwise claimed.
Numerous modifications and adaptations will be readily apparent to
those of ordinary skill in this art.
* * * * *
References