U.S. patent application number 12/580198 was filed with the patent office on 2010-02-11 for wireless communication out of range indication.
This patent application is currently assigned to APPLE INC.. Invention is credited to Michael M. LEE, Christopher McKILLOP, Stephan Vincent SCHELL.
Application Number | 20100035598 12/580198 |
Document ID | / |
Family ID | 39494951 |
Filed Date | 2010-02-11 |
United States Patent
Application |
20100035598 |
Kind Code |
A1 |
LEE; Michael M. ; et
al. |
February 11, 2010 |
WIRELESS COMMUNICATION OUT OF RANGE INDICATION
Abstract
With respect to a wireless network, an out of range warning
provides an estimate of an amount of time remaining until a
wireless device is out of range of the wireless network. In this
way, the user is presented with an opportunity to take corrective
measures, if desired.
Inventors: |
LEE; Michael M.; (San Jose,
CA) ; McKILLOP; Christopher; (La Honda, CA) ;
SCHELL; Stephan Vincent; (San Mateo, CA) |
Correspondence
Address: |
BEYER LAW GROUP LLP/APPLE INC.
P.O. BOX 1687
CUPERTINO
CA
95015-1687
US
|
Assignee: |
APPLE INC.
Cupertino
CA
|
Family ID: |
39494951 |
Appl. No.: |
12/580198 |
Filed: |
October 15, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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11563655 |
Nov 27, 2006 |
7630707 |
|
|
12580198 |
|
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Current U.S.
Class: |
455/421 |
Current CPC
Class: |
H04W 64/006
20130101 |
Class at
Publication: |
455/421 |
International
Class: |
H04M 11/00 20060101
H04M011/00 |
Claims
1. A method of providing by a wireless device an out of range
warning with respect to a wireless signal provider, comprising:
receiving a wireless transmission from the wireless signal
provider; determining a current quality metric for the received
wireless transmission; determining a change of the current quality
metric with respect to time; if the change of the current quality
metric with respect to time is a negative value, then estimating a
period of time until the wireless device is out of range of the
wireless signal provider; and issuing the out of range warning that
includes the estimated period of time until the wireless device is
out of range of the wireless signal provider.
2. The method as recited in claim 1, wherein the determining a
change of the quality metric with respect to time comprises:
associating a time stamp with the current quality metric; storing
the current quality metric and the associated time stamp as a
previous quality metric; updating the current quality metric and
the time stamp; calculating a time rate of change of the quality
metric; wherein the calculating the time rate of change of the
quality metric, comprises: subtracting the updated quality metric
from the previous quality metric to form a delta quality metric;
and dividing the delta quality metric by a time interval
corresponding to difference between the current time stamp and the
previous time stamp.
3. The method as recited in claim 2, wherein calculating the
estimated period of time until the wireless device is out of range
of the wireless network, comprises: determining a difference
between the current quality metric and a quality metric
corresponding to the effective boundary of the wireless network;
and dividing the difference by the time rate of change of the
quality metric.
4. The method as recited in claim 1, wherein the wireless device
includes a GPS circuit arranged provide a current location of the
wireless device.
5. The method as recited in claim 4, further comprising: using the
GPS circuit to, determine if the wireless device is in motion; and
if the wireless device is determined to be in motion, determine the
velocity and direction of motion of the wireless device.
6. The method as recited in claim 5, further comprising: providing
a change of course to a user of the wireless device to take at the
current velocity that causes the time rate of change of the quality
metric to change from the negative value to a non-negative
value.
7. The method as recited in claim 1, wherein the out of range
warning is issued to at least one other communication device
currently in communication with the wireless device.
8. A portable wireless device, comprising: a GPS circuit arranged
to determine a current location of the portable wireless device; a
wireless transceiver unit, the wireless transceiver unit arranged
to at least receive a wireless transmission from a wireless signal
provider; a processor, the processor arranged to, determine a
current quality metric for the received wireless transmission;
determine a change of the current quality metric with respect to
time; if the change of the current quality metric with respect to
time is a negative value, then estimate a period of time until the
wireless device is out of range of the wireless signal provider;
and issue the out of range warning that includes the estimated
period of time.
9. The portable wireless device as recited in claim 8, further
comprising: using the GPS circuit in combination with the processor
to, determine if the wireless device is in motion; and if the
wireless device is determined to be in motion, determine the
velocity and direction of motion of the wireless device.
10. The portable wireless device as recited in claim 9, further
comprising: wherein if the wireless device is determined to be in
motion and the time rate of change of the quality metric is
negative, then the processor suggests to a user of the wireless
device a change of course to take at the current velocity that
causes the time rate of change of the quality metric to change from
the negative value to a non-negative value.
11. The portable wireless device as recited in claim 8, wherein the
out of range warning is issued to at least one other communication
device currently in communication with the portable wireless
device.
12. Computer readable medium for storing instructions executable by
a processor for providing by a wireless device an out of range
warning with respect to a wireless signal provider, the computer
readable medium comprising: computer code for receiving a wireless
transmission from the wireless signal provider; computer code for
determining a current quality metric for the received wireless
transmission; computer code for determining a change of the current
quality metric with respect to time; computer code for estimating a
period of time until the wireless device is out of range of the
wireless signal provider if the change of the current quality
metric with respect to time is a negative value; and computer code
for issuing the out of range warning that includes the estimated
period of time.
13. The computer readable medium as recited in claim 12, wherein
the computer code for determining a change of the quality metric
with respect to time comprises: computer code for associating a
time stamp with the current quality metric; computer code for
storing the current quality metric and the associated time stamp as
a previous quality metric; computer code for updating the current
quality metric and the time stamp; computer code for calculating a
time rate of change of the quality metric; wherein the computer
code for calculating the time rate of change of the quality metric,
comprises: computer code for subtracting the updated quality metric
from the previous quality metric to form a delta quality metric;
and computer code for dividing the delta quality metric by a time
interval corresponding to difference between the current time stamp
and the previous time stamp.
14. The computer readable medium as recited in claim 13, wherein
calculating the estimated period of time until the wireless device
is out of range of the wireless network, comprises: determining a
difference between the current quality metric and a quality metric
corresponding to the effective boundary of the wireless network;
and dividing the difference by the time rate of change of the
quality metric.
15. The computer readable medium as recited in claim 12, wherein
the wireless device includes a GPS circuit arranged provide a
current location of the wireless device.
16. The computer readable medium as recited in claim 15, further
comprising: using the GPS circuit to, determine if the wireless
device is in motion; and if the wireless device is determined to be
in motion, determine the velocity and direction of motion of the
wireless device.
17. The computer readable medium as recited in claim 16, further
comprising: providing a change of course of the wireless device to
take at the current velocity that causes the time rate of change of
the quality metric to change from the negative value to a
non-negative value.
18. The computer readable medium as recited in claim 12, wherein
the out of range warning is issued to at least one other
communication device currently in communication with the wireless
device.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a Continuation of and claims priority
under 35 USC .sctn.120 to U.S. patent application Ser. No.
11/563,655 filed Nov. 27, 2006.
BACKGROUND OF THE INVENTION
[0002] 1. Field of Invention
[0003] This invention relates in general to wireless networks and
more particularly to providing an out of range indication.
[0004] 2. Description of Related Art
[0005] Recent developments in consumer electronics have included
the introduction of wireless personal communication devices such as
cell phones, personal walkie-talkies, PDAs (Personal Digital
Assistants) and other portable electronic devices. Such devices can
be used in many places to wirelessly connect to the Internet, play
games, email and other messaging functions as well as provide for
personal communications.
[0006] Many factors can influence the quality of communications
received and/or transmitted to/from a wireless device, including
geography, weather, physical obstacles such as foliage and
buildings, battery power etc. For example, buildings and other
structures can cause interference with the desired communication
signals. Such interference typically depends on the method of
construction used and the design of the building or other
structures and other factors. A user's distance from a transceiver
can also result in poor signal quality that can result in
unexpected (and annoying) dropped calls, for example.
[0007] In order to provide notice of poor signal quality, some
wireless devices have a one-way signal strength indicator that is a
rough estimator of quality of the radio frequency signal between
the covering base station and the receiving wireless device. For
example, U.S. Pat. No. 5,809,414 to Coverdale et al. selectively
provides to a user a signal strength indication using one or more
pre-selected criteria. Unfortunately, however, this signal strength
indicator provides the user with an indication of the signal
quality only at that particular moment in time which is usually too
late to take corrective measures in order to avoid the lost
wireless signal or at least mitigate the effects of the lost signal
when, or if, it occurs.
[0008] Therefore, what is desired is an out of range indication
suitable for use in a wireless network.
SUMMARY OF THE INVENTION
[0009] The invention pertains to methods and systems for providing
an out of range warning to a user of a wireless device in a
wireless network. In one embodiment, the out of range warning can
provide an estimate of an amount of time remaining until the
wireless device is out of range of the wireless network. In this
way, the user is presented with an opportunity to take corrective
measures, if desired.
[0010] The invention can be implemented in numerous ways, including
as a method, system, device, apparatus, consumer product, or
computer readable medium. Several embodiments of the invention are
discussed below.
[0011] As a method for providing an out of range warning by a
wireless device with respect to a wireless network, one embodiment
of the invention includes at least the acts of: receiving a
wireless transmission; determining a current quality metric for the
received wireless transmission; estimating a period of time until
the wireless device is out of range of the wireless network; and
issuing the out of range warning that includes the estimated period
of time.
[0012] As computer program product, one embodiment of the invention
includes at least: computer code for receiving a wireless
transmission; computer code for determining a current quality
metric for the received wireless transmission; computer code for
estimating a period of time until the wireless device is out of
range of the wireless network; computer code for issuing the out of
range warning that includes the estimated period of time; and
computer readable medium for storing the computer code.
[0013] As an apparatus, one embodiment of the invention includes a
receiving unit arranged to receive a wireless transmission. The
apparatus also includes a processing unit coupled to the receiving
unit arranged to determine a current quality metric for the
received wireless transmission, estimate a period of time until the
wireless apparatus is out of range of the wireless network, and
issue the out of range warning that includes the estimated period
of time.
[0014] Other aspects and advantages of the invention will become
apparent from the following detailed description, taken in
conjunction with the accompanying drawings, illustrating by way of
example the principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The invention will be better understood by reference to the
following description taken in conjunction with the accompanying
drawings
[0016] FIG. 1 shows representative wireless device (such as a cell
phone) in accordance with an embodiment of the invention.
[0017] FIG. 2 shows representative wireless network having base
station in wireless communication with wireless device of FIG. 1 in
accordance with an embodiment of the invention.
[0018] FIG. 3 and FIG. 6 show a relationship between QoWS(d) and
probability of dropping a call P.sub.drop in accordance with an
embodiment of the invention.
[0019] FIG. 4 illustrates a representative contour map of QoWS(d)
using lines of constant QoWS(n) in accordance with an embodiment of
the invention.
[0020] FIG. 5 shows a simplified "slice" of contour map of FIG. 4
in accordance with an embodiment of the invention.
[0021] FIG. 7 shows a flowchart detailing a process for providing
an out of range warning in accordance with an embodiment of the
invention.
DETAILED DESCRIPTION OF SELECTED EMBODIMENTS
[0022] Reference will now be made in detail to selected embodiments
of the invention an example of which is illustrated in the
accompanying drawings. While the invention will be described in
conjunction with a selected embodiment, it will be understood that
it is not intended to limit the invention to one particular
embodiment. To the contrary, it is intended to cover alternatives,
modifications, and equivalents as may be included within the spirit
and scope of the invention as defined by the appended claims.
[0023] The embodiments described herein provide a human observable
out of range warning to a user of a mobile wireless device that the
user is moving out of range of a wireless network. Such warnings
can take many forms, such as a vibratory warning, audible warning,
visual, etc. A particularly useful embodiment provides in addition
to the human observable out of range indication, an estimate of an
amount of time remaining until the user is projected to be out of
range if no corrective action is taken. It should be noted that the
term "projected to be out of range" could be defined in any number
of ways. For example, in the context of a cellular telephone,
"projected to be out of range" can be taken as the probability of
dropping a call is greater than a pre-selected threshold (>98%,
for example).
[0024] In the described embodiments, both the out of range warning
and the estimate of time remaining until the user is projected to
be out of range are based upon characterizing the time dependent
behavior of wireless signal quality parameters. In those cases
where the time dependent behavior indicates that the mobile
wireless device is moving from a region of higher wireless signal
quality to a region of lower wireless signal quality, an estimate
of the amount of time until the wireless device is projected to be
out of range is calculated and compared to a pre-determined
threshold. If the estimated amount of time until the wireless
device projected to be out of range is less than the threshold, a
tangible warning is issued to that effect. In some embodiments, the
tangible warning not only notifies the user of the wireless device
of the impending loss of signal, but also if no corrective action
is taken, how long before the signal is effectively lost. In this
way, warnings are only issued for those situations where the loss
of signal would affect the user in the here and now and thereby
prevent unnecessary (and potentially annoying) warnings being
issued. It should also be noted that in a number of embodiments,
the status of the wireless device (active vs. inactive) can be
taken into account in deciding whether or not to issue the warning
and under what conditions. Clearly if the wireless device is
active, then more stringent timing requirements would be necessary
as opposed to those situations when the wireless device is inactive
(such as in a standby mode). In some embodiments (such as those
involving communication devices such as cell phones, PDAs, etc.),
the warning can be wirelessly transmitted to any other person
currently in communication with the user of the wireless device
indicating that the call may be dropped. The invention is also well
suited to be incorporated with mobile devices that are equipped
with guidance systems (GPS, accelerometers, etc.) thereby providing
an accurate value of the location, velocity, acceleration,
elevation, etc. of the wireless mobile device that can be used to
give a more precise value of the time remaining until the out of
boundary condition is reached.
[0025] The embodiments will now be described in the context of a
wireless device that can be either digital or analog in nature.
Such devices can include a pocket sized cell phone that in addition
to the standard voice function of a telephone can support many
additional services such as SMS for text messaging packet switching
for access to the Internet and MMS for sending and receiving photos
and video. The wireless device can also include personal digital
assistants (PDAs), wireless multimedia players, and the like.
[0026] FIG. 1 shows representative wireless device 100 (such as a
cell phone) in accordance with an embodiment of the invention. As a
cell phone, wireless device 100 includes processor 102 that
pertains to a microprocessor or controller for controlling the
overall operation of wireless device 100 that stores data in RAM
104 and Read-Only Memory (ROM) 106. ROM 106 can store programs,
utilities or processes to be executed in a non-volatile manner
whereas RAM 104 provides volatile data storage such as currently
called phone numbers, ring tones, etc. Wireless device 100 also
includes user input device 108 that allows a user to interact with
wireless device 100. For example, user input device 108 can take a
variety of forms, such as a button, keypad, dial, etc. Still
further, wireless device 100 includes display 110 (screen display)
that can be controlled by processor 102 to display information to
the user. A data bus can facilitate data transfer between at least
ROM 106, RAM 104, processor 102, and CODEC 112 that produces analog
output signals for audio output device 114 (such as a speaker).
Speaker 114 can be located internal to wireless device 100 or
external to wireless device 100. For example, headphones or
earphones that connect to wireless device 100 would be considered
an external speaker. Wireless interface 116 operates to receive
information from processor 102 that opens a wireless channel
(either voice or data) for transmission and reception using, for
example, RF carrier waves, infrared (IR) signals, etc.
[0027] FIG. 2 shows representative wireless network 200 having base
station 202 in wireless communication with wireless device 100 in
accordance with an embodiment of the invention. It should be noted
that wireless network 200 can utilize any appropriate wireless
technology such as radio-frequency (also referred to as RF that
includes WiFi, Bluetooth, GCS, PCM, etc.) or optical (Infrared also
referred to as IR), etc. In the described embodiment, base station
202 transmits wireless signal WS having signal strength S that (in
the case of both RF and optical signals) on the average varies
inversely with the square of distance d (i.e., S.varies.1/d.sup.2)
from base station 202. It should be noted that other factors can
also affect signal strength S. Such factors include but are not
limited to the local terrain, local weather, physical obstacles
such as buildings, power lines, and so on. However, for sake of
simplicity only, it is assumed for the present discussion that no
such factors are present and the only variation in signal strength
S is due to distance d from base station 202.
[0028] Typically, the quality of wireless signal S (referred to
hereinafter as QoWS) at a receiver decreases as the distance
between the receiver and a transmitter increases. In particular, if
QoWS as a measure of the reliability and usability of wireless
network 200 is related to signal strength S (i.e., QoWS tracks S),
QoWS is then (approximately) inversely related to distance d from
base station 202 as Eq. (1):
QoWS.varies.1/d.sup.2 Eq. (1)
It should be noted, however, that in more general terms, QoWS is
related to distance d as Eq. (2):
QoWS.varies.i/d.sup.m Eq. (2)
where the value of m depends upon the underlying network quality
metric used to generate QoWS. For example, if wireless network 200
is a cellular telephone network (where QoWS is typically taken from
a user's viewpoint), one can base QoWS for such a network on a
quality metric referred to as coverage where signal strength S is
measured using test equipment that, in turn, can be used to
estimate the size of the cell. In this case, therefore, .apprxeq.2
and QoWS closely tracks signal strength S throughout network 200
when configured as a cellular telephone network.
[0029] However, since the choice of underlying quality metric(s)
depends upon many factors not the least of which include the type
of network (cellular telephone, broadband, etc.), what is deemed to
be the most appropriate quality metric to be used may or may not be
tightly coupled to signal strength S. For example, as discussed
above, cellular telephone networks can utilize signal strength S as
an underlying quality metric (i.e., coverage) whereas a broadband
type network (such as WiFi, Bluetooth, etc.) can be characterized
using QoWS based upon the probability of packet losses or delays in
already accepted calls and the probability that a new incoming call
will be rejected. In this case, QoWS can have a very different
relationship to distance d from base station 202 and the value of m
can only be determined empirically.
[0030] In those cases where QoWS is, on average, inversely
proportional to dm, m is an empirically determined real number
between 2 and 4 and "average" is understood to mean a spatial or
ensemble average taken over a collection of possible locations for
the wireless device, such that all locations in this collection are
similar to the present location with regards to distance, local
terrain, weather, obstacles, and proximity of the device to the
user's body parts. However, if QoWS is computed in some other way
(such as in the Bluetooth embodiment described below) then the
inverse power-law model is unlikely to hold at all and an
empirically derived relationship is more appropriate.
[0031] Accordingly, in one embodiment of the invention, wireless
network 200 can be characterized based upon an underlying quality
metric that is directly related to signal strength S (much like
coverage for a cellular telephone network). In particular, wireless
network 200 is characterized in terms of spatially dependent
quality of wireless signal QoWS(d), where `d` is the distance from
the base station (it should be noted that in Cartesian coordinates,
d.sup.2=x.sup.2+y.sup.2). Using this convention, as distance d
between wireless device 100 and base station 202 increases, QoWS(d)
decreases until at boundary 204, QoWS(d) is so low that effective
wireless communication between wireless device 100 and base station
202 is unlikely. In the parlance of a cellular telephone network,
the call has been dropped and a new communication link must be
established in order to continue the conversation (that may or may
not be possible in the given circumstances). Clearly this is an
annoying situation at best and should be avoided if at all
possible.
[0032] In this way, QoWS(d) provides a measure of the likelihood
that a stable communication link can be established and maintained
between base station 202 and wireless device 100. FIG. 3 shows a
representative relationship between QoWS(d) and call drop
probability P.sub.drop in accordance with an embodiment of the
invention. Since there is an inverse relationship between QoWS(d)
and call drop probability P.sub.drop, if QoWS(d) is high, then
probability P.sub.drop is low since there is a high probability
that a stable communication link between base station 202 and
wireless device 100 can be both established and maintained and
therefore the number of dropped calls is concomitantly low.
However, if QoWS(d) is low, then call drop probability P.sub.drop
is high since a stable communication link can not, in all
probability, be established in the first place or if established
will not be sustainable due to low signal to noise ratio (S/N) for
an analog network or a large number of dropped packets in a digital
network, for example, resulting in a high likelihood of dropped
calls.
[0033] FIG. 4 illustrates a representative contour map 400 of
QoWS(d) using lines of constant QoWS(n) in accordance with an
embodiment of the invention. For example, QoWS(0) represents a
baseline value QoWS for all wireless devices 100 located at
baseline distance d.sub.0 whereas QoWS(1) represents a lower value
of QoWS for all wireless devices 100 located at distance d.sub.1
and so on until at distance d.sub.6 (QoWS (6) in this example) is
reached that any further characterization is pointless since it is
beyond boundary 204 being the effective range of wireless network
200. It should be noted that the distance between contours line is
not necessarily equal.
[0034] When wireless device 100 is effectively immobile (such as a
desktop computer in a local WiFi network), the positioning of
wireless device 100 in order to optimize QoWS can be accomplished
simply by determining the particular value of d that coincides with
a local maximum value of QoWS. However, in the context of the
present embodiment, wireless device 100 is a mobile wireless
device, such as a cellular telephone, PDA, etc. where the contours
of wireless network 200 are unknown to a user and therefore can not
be relied upon to "cherry pick" a location for optimal reception.
If it is assumed that signal strength S is constant, any change in
QoWS experienced by mobile wireless device 100 is due only to
changes in the spatial distribution of QoWS. For example, FIG. 5
shows a simplified "slice" 500 of contour map 400 in accordance
with an embodiment of the invention. By slice it is meant that only
those values of contour map 400 located on a plane surface (such as
y=0 in this case) are shown thereby greatly simplifying the
analysis. As shown, as wireless device 100 moves out from base
station 202, QoWs(d) is a steadily decreasing function. More
specifically,
QoWS(0)>QoWS(1)>QoWS(2)>QoWS(3) . . . >QoWS(6). Eq.
(3)
[0035] Therefore, by keeping track of and comparing current QoWS
(k) with previous QoWS (k-1) over time, a rate of change of QoWS
can be estimated that can be used to determine if mobile wireless
device 100 is approaching boundary 204 and how fast. For example,
if mobile wireless device 100 is moving from a region of relatively
higher QoWS to a region of relatively lower QoWS (representing a
trend to decreasing QoWS), then there is a possibility that if the
trend continues long enough, mobile wireless device 100 will reach
and even cross boundary 204 with a likely loss of signal.
[0036] For example (referring to FIG. 5), if mobile wireless device
100 has moved from location x=4 at time t.sub.0 to location x=3 at
time t.sub.1 (towards base station 202) then it can be inferred
that mobile wireless device 100 is moving from a region of lower
QoWS to one of higher QoWS (since QoWS(4)<QoWS (3)) and
therefore no out of range warning is necessary. However, if mobile
wireless device 100 has moved from location x=3 at time t.sub.0 to
location x=4 at time t.sub.1 (away from base station 202) then it
can be inferred that mobile wireless device 100 is moving from a
region of higher QoWS to one of lower QoWS and therefore an out of
range warning may be necessary since as illustrated in FIG. 6, any
change in QoWS results in a commensurate change in call drop
probability P.sub.drop. For example, when wireless device 100 is
moving away from base station 202 into a region of comparatively
lower QoWS, then call drop probability P.sub.drop increases from
P.sub.drop1 to P.sub.drop2 (indicating that the probability of
dropping a call has increased). In those cases that wireless device
100 has entered a region of such low QoWS (which in this example is
designated QoWS*) that call drop probability P.sub.drop exceeds
P.sub.thresh, then an out or range warning can be issued without
further ado (this can be useful in those situations where a user
has walked behind a wall, for example, where QoWS drops
rapidly).
[0037] However, if mobile wireless device 100 is experiencing a
decrease in QoWS (for any reason) but not of such magnitude that
that call drop probability P.sub.drop does not exceed P.sub.thresh,
then in order to determine if an out of range warning will be
issued, an estimate of an amount of time T remaining until the out
of range condition is actually realized is calculated based upon
the time rate of change of QoWS and the difference between the most
recent value of QoWS and QoWS*. In other words,
T = .DELTA. Q .times. ( 1 ( Q T ) ) EQ . ( 4 ) ##EQU00001##
where d(Q)/dt is the time rate of change of QoWS and .DELTA.Q is
the difference between the most recent QoWS and QoWS*.
[0038] In this way, once notified, a user has the option to change
course, stop the conversation, or any other preventive measures
designed to avoid having a call dropped or mitigating the effects
of an imminent dropped call. For example, if a user realizes that a
current call is in imminent peril of being dropped, the user can
notify the other party and hang up or warn them to expect a
possible lost connection, etc.
[0039] A specific example of an implementation of the invention
will now be described where the wireless network 200 is based upon
Bluetooth.RTM. protocol. It should be noted that by Bluetooth.RTM.
protocol it is meant a wireless protocol according to any of prior,
present or future versions of a wireless protocol specification
promulgated by the Bluetooth.RTM. SIG, Inc. or its equivalent
and/or successor organizations.
[0040] In a Bluetooth.RTM. based wireless network, communication
between any two wireless devices can be thought of as occurring in
four layers, a physical link layer, a logical link layer, a data
link layer, and an application layer. The physical link can be
formed between any two devices that transmit packets between them
and can also be used as a transport for one or more logical links.
The logical link layer (that can be thought of as being "above" the
physical layer) supports, for example, uni-cast synchronous,
asynchronous and isochronous traffic, as well as broadcast traffic.
It should be noted that traffic on logical links can be multiplexed
onto the physical link layer by occupying slots assigned by a
scheduling function in the resource manager. The data link layer
("above" the logical link layer) includes a Logical Link Control
and Adaptation Layer (also referred to as L2CAP) that provides a
channel-based abstraction to applications and services and can
carries out segmentation and reassembly of application data and
multiplexing and de-multiplexing of multiple channels over a shared
logical link. The application layer ("above" data link layer)
includes one or more applications that, according to the
Bluetooth.RTM. protocol, can be the end user and/or originator of
the data being transmitted.
[0041] In an embodiment of the invention, an indication of
communication activity at any of the layers (such as an error rate
of the communication at that layer) can be used as the underlying
quality metric for a Bluetooth.RTM. based wireless network. One
such communication activity that can be used as an underlying
quality metric for a Bluetooth based wireless network is the L2CAP
"Echo Request" command and corresponding L2CAP "Echo Response"
command. As set forth in the Bluetooth.RTM. L2CAP specification,
Echo requests are used to request a response from a remote L2CAP
entity. These requests can be used for testing the wireless link or
for passing vendor specific information using the optional data
field. The Bluetooth.RTM.protocol requires that L2CAP entities
respond to a valid Echo Request packet with an Echo Response packet
upon receiving a valid Echo Request that matches the identifier
sent in the Request. An error rate statistic can generated based on
Echo Request packets and the relative number of Echo Response
packets for a particular time period (a number of L2CAP Echo
Response packets actually received relative to the number of L2CAP
Echo Request commands sent). This "ping" and "ping response" model
(such as that provided by L2CAP Echo Request and L2CAP Echo
Response) can be used for any of a number of other multilayer
wireless communication protocols. In this way, a Bluetooth wireless
device can ascertain current wireless signal quality and a time
rate of change of signal quality using the L2CAP Echo/Response
model.
[0042] FIG. 7 shows a flowchart detailing a process 700 for
providing an out of range warning in accordance with an embodiment
of the invention. Process 700 begins at 702 by initializing a
mobile wireless device by, for example, powering up the device,
allowing the device to register itself in the wireless network in
which it is embedded, displaying all graphical user interfaces,
updating voicemail indicators, etc. Once the mobile wireless device
has been initialized, at 704 a wireless transmission is received
and at 706 a quality metric of the received wireless digital
transmission is determined. At 708, if the quality metric is less
than a first threshold, then an out of range warning is issued at
710, otherwise at 712 a time rate of change of the quality metric
is calculated. If at 714, the time rate of change of the quality
metric less than zero, then at 716, an estimate of an amount of
time remaining until the wireless device is likely to be out of
range of the wireless communication system is calculated,
otherwise, the quality metric of the received wireless transmission
is updated at 718. At 720, if the estimate of the amount of time
remaining until the wireless device is likely to be out of range of
the wireless network is less than a second threshold, then at 722
an out of range warning that includes a corresponding amount of
time until the wireless device is out of range of the wireless
network is issued, otherwise it is not.
[0043] While this invention has been described in terms of a
preferred embodiment, there are alterations, permutations, and
equivalents that fall within the scope of this invention. It should
also be noted that there are many alternative ways of implementing
both the process and apparatus of the present invention. It is
therefore intended that the invention be interpreted as including
all such alterations, permutations, and equivalents as fall within
the true spirit and scope of the present invention.
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