U.S. patent application number 12/938934 was filed with the patent office on 2011-02-24 for network formation in asset-tracking system based on asset class.
Invention is credited to Robert W. TWITCHELL, JR..
Application Number | 20110047015 12/938934 |
Document ID | / |
Family ID | 46332108 |
Filed Date | 2011-02-24 |
United States Patent
Application |
20110047015 |
Kind Code |
A1 |
TWITCHELL, JR.; Robert W. |
February 24, 2011 |
NETWORK FORMATION IN ASSET-TRACKING SYSTEM BASED ON ASSET CLASS
Abstract
A plurality of wireless transceivers are associated with assets
and each transceiver is assigned a class designation representative
of an attribute, characteristic, relation, or behavior of its
respective asset. Class based network formation routines are
utilized to establish hierarchical networks based on asset classes,
and the asset class is used by each transceiver to screen
communications intended for receipt by transceivers of the same
class. The overall wireless data communication network results in
reduced power consumption and signal interference in asset tracking
applications. The transceivers may include a query handling routine
for forming a dynamically distributed hierarchical database system.
Furthermore, a recipient transceiver selectively receives
communications from other local transceivers by transmitting at
incrementally stronger power levels to successive groups of
transceivers, and receiving reply transmissions only from a limited
number of the transceivers that excludes those transceivers from
which communications already are received.
Inventors: |
TWITCHELL, JR.; Robert W.;
(Suwanee, GA) |
Correspondence
Address: |
TILLMAN WRIGHT, PLLC
PO BOX 49309
CHARLOTTE
NC
28277-0076
US
|
Family ID: |
46332108 |
Appl. No.: |
12/938934 |
Filed: |
November 3, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12882574 |
Sep 15, 2010 |
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12938934 |
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12774575 |
May 5, 2010 |
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12882574 |
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12411205 |
Mar 25, 2009 |
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12774575 |
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11161542 |
Aug 8, 2005 |
7522568 |
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12411205 |
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10604032 |
Jun 23, 2003 |
6934540 |
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11161542 |
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09681282 |
Mar 13, 2001 |
6745027 |
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10604032 |
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PCT/US01/49513 |
Dec 26, 2001 |
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10604032 |
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09681282 |
Mar 13, 2001 |
6745027 |
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PCT/US01/49513 |
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10514336 |
Nov 12, 2004 |
7209771 |
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PCT/US03/14987 |
May 14, 2003 |
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11161542 |
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09681282 |
Mar 13, 2001 |
6745027 |
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10514336 |
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PCT/US01/49513 |
Dec 26, 2001 |
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PCT/US03/14987 |
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09681282 |
Mar 13, 2001 |
6745027 |
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PCT/US01/49513 |
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60257637 |
Dec 22, 2000 |
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60257637 |
Dec 22, 2000 |
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60257637 |
Dec 22, 2000 |
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60257398 |
Dec 22, 2000 |
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60257637 |
Dec 22, 2000 |
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60257637 |
Dec 22, 2000 |
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60257637 |
Dec 22, 2000 |
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60257398 |
Dec 22, 2000 |
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60380195 |
May 14, 2002 |
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60380670 |
May 16, 2002 |
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60595233 |
Jun 16, 2005 |
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60642632 |
Jan 10, 2005 |
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60687073 |
Jun 3, 2005 |
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60687415 |
Jun 3, 2005 |
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60688737 |
Jun 8, 2005 |
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60691574 |
Jun 17, 2005 |
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60691718 |
Jun 17, 2005 |
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60691884 |
Jun 17, 2005 |
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60696159 |
Jul 1, 2005 |
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Current U.S.
Class: |
705/14.4 ;
340/10.33 |
Current CPC
Class: |
H04Q 2209/43 20130101;
Y02D 70/40 20180101; H04W 52/0229 20130101; H04W 16/14 20130101;
Y02D 70/122 20180101; Y02D 70/164 20180101; G06Q 10/0832 20130101;
Y02D 70/142 20180101; Y02D 70/144 20180101; G06Q 10/08 20130101;
H04Q 9/00 20130101; Y02D 70/166 20180101; G06Q 10/087 20130101;
Y02D 30/70 20200801; Y02D 70/22 20180101; G06Q 10/0833 20130101;
H04Q 2209/883 20130101; H04Q 2209/20 20130101; Y02D 70/23 20180101;
H04W 8/26 20130101; H04W 84/18 20130101; H04B 1/38 20130101; G06Q
30/0241 20130101 |
Class at
Publication: |
705/14.4 ;
340/10.33 |
International
Class: |
H04Q 5/22 20060101
H04Q005/22; G06Q 30/00 20060101 G06Q030/00 |
Claims
1. (canceled)
2. A method comprising: detecting a wake up event through a radio
frequency sensor interface of a device, putting said device into an
operative mode including powering a radio frequency communication
interface of said device and transmitting at least one advertising
message via the radio frequency communication interface in response
to detection of said wake up event, determining whether a response
to said at least one advertising message is received at the radio
frequency communication interface within a defined time frame; and
putting said device into a passive operation mode including
shutting down the radio frequency communication interface for a
predetermined period of time, if no response is received within
said defined time frame, wherein in said passive mode wake up
events are ignored.
3. The method according to claim 2, further comprising: if a
response is received within said defined time frame, setting up a
connection and transmitting data in accordance with said
response.
4. The method according to claim 2, further comprising: activating
only necessary radio components which are needed to detect said
wake up event prior to said detection of said wake up event.
5. The method according to claim 2, further comprising: putting
said radio device into an operative mode after said predetermined
period of time has expired.
6. The method according to claim 5, further comprising:
transmitting an advertising message via said radio frequency
communication interface after putting said radio device into an
operative mode.
7. The method according to claim 2, wherein said detecting said
wake up event comprises receiving energy transmitted from another
device in a determined frequency band, amplifying said received
energy, and detecting the increased energy level after
amplifying.
8. The method according to claim 2, wherein said detecting said
wake up event comprises receiving transmitted energy from another
device, and utilizing the received energy for putting said device
into an operational mode.
9. The method according to claim 2, further comprising receiving a
sensor output from a sensor provided in said radio device said
sensor responsive to physical contact of a person or another
device, and putting said device into an operative mode responsive
to said sensor output.
10. A computer readable medium comprising program code stored
thereon, said program code for running on a processor configured
to: detect wake up event through a radio frequency sensor interface
of a device, put said device into an operative mode including
powering a radio frequency communication interface of said device
in response to detection of said wake up event, transmit at least
one advertising message via the radio frequency communication
interface, determine whether a response to said at least one
advertising message is received at the radio frequency
communication interface within a defined time frame, and put said
device into a passive operation mode including shutting down the
radio frequency communication interface for a predetermined period
of time if no response to is received within said defined time
frame, wherein in said passive mode wake up events are ignored.
11. An apparatus comprising: a transceiver configured to transmit
and receive data wirelessly, a controller configured to control the
operative mode of said apparatus, a timer, and a detector
configured to detect a wake up event and to notify said controller
to put said apparatus into an operative mode if a wake up event is
detected, wherein said transceiver is further configured to
transmit at least one advertising message, wherein said controller
is further configured to put said apparatus into a passive mode in
response to said transceiver receiving no response to said at least
one transmitted advertising message, wherein said timer is
configured to be active for a predetermined period of time when the
apparatus is put into a passive mode, and said controller is
further configured to be inactive while said timer is active so as
to avoid said apparatus responding to wake up events while in said
passive mode.
12. The apparatus according to claim 11, further comprising a data
interface connected to said controller, being adapted to exchange
data with components connected to said controller.
13. The apparatus according to claim 11, wherein said controller
further comprises at least one sensor responding to physical
proximity.
14. An apparatus comprising: means controlling the operative mode
of said apparatus, means for detecting a wake up event and for
notifying said means for controlling to put said apparatus into an
operative mode in response to detecting said wake up even, means
for transmitting at least one advertising message in response to
said apparatus being put into an operative mode, and means for
notifying said means for controlling to put said apparatus into a
passive mode in response to receiving no response to said at least
one transmitted advertising message; wherein said means for
controlling further comprises timer means for being active for a
predetermined period of time when the apparatus is put into a
passive mode, and for keeping said means for controlling inactive
while said timer means is active so as to avoid said apparatus
responding to wake up events while in said passive mode.
15. An apparatus comprising a processor configured to: detect a
wake up event through a radio frequency sensor interface of said
apparatus; put said apparatus into an operative mode including
powering a radio frequency communication interface of said
apparatus and transmitting at least one advertising message via the
radio frequency communication interface in response to detection of
said wake up event; determine whether a response to said at least
one advertising message is received at the radio frequency
interface within a defined time frame; and put said apparatus into
a passive operation mode including shutting down the radio
frequency communication interface for a predetermined period of
time, if no response is received within said defined time frame,
wherein in said passive mode wake up events are ignored.
16. A method comprising: detecting a wake up event through a radio
frequency interface of a device, putting said device into an
operative mode including powering a radio frequency communication
interface of said device and transmitting at least one ping
transmission via the radio frequency communication interface in
response to detection of said wake up event, determining whether a
response to said at least one ping transmission is received at the
radio frequency communication interface within a defined time
frame; and putting said device into an off-duty mode including
shutting down the radio frequency communication interface for a
predetermined period of time until a next duty cycle, if no
response is received within said defined time frame, wherein in
said off-duty mode wake up events are ignored.
17. A method comprising: detecting a wake up event via a radio
frequency component of a device, putting said device into an
operative mode including powering a radio frequency communication
component of said device and transmitting at least one ping
transmission via the radio frequency communication component in
response to detection of said wake up event, determining whether a
response to said at least one ping transmission is received at the
radio frequency communication component within a defined time
frame; and putting said device into an off-duty mode including
shutting down the radio frequency communication component for a
predetermined period of time until a next duty cycle, if no
response is received within said defined time frame, wherein in
said off-duty mode wake up events are ignored.
18. A computer readable medium comprising program code stored
thereon, said program code for running on a processor configured
to: detect a wake up event through a radio frequency sensor
interface of a device, put said device into an operative mode
including powering a radio frequency communication interface of
said device in response to detection of said wake up event,
transmit a ping transmission via the radio frequency communication
interface, determine whether a response to said ping transmission
is received at the radio frequency communication interface within a
defined time frame, and put said device into an off-duty mode
including shutting down the radio frequency communication interface
for a predetermined period of time if no response is received
within said defined time frame, wherein in said off-duty mode wake
up events are ignored.
19. A computer readable medium comprising program code stored
thereon, said program code for running on a processor configured
to: detect a wake up event via a radio frequency component of a
device, put said device into an operative mode including powering a
radio frequency communication component of said device in response
to detection of said wake up event, transmit a ping transmission
via the radio frequency communication component, determine whether
a response to said ping transmission is received at the radio
frequency communication component within a defined time frame, and
put said device into an off-duty mode including shutting down the
radio frequency communication component for a predetermined period
of time if no response is received within said defined time frame,
wherein in said off-duty mode wake up events are ignored.
20. An apparatus comprising: a transceiver configured to transmit
and receive data wirelessly, a controller configured to control the
operative mode of said apparatus, a timer, and a detector
configured to detect a wake up event and to notify said controller
to put said apparatus into an operative mode if a wake up event is
detected, wherein said transceiver is further configured to
transmit at least one ping transmission, wherein said controller is
further configured to put said apparatus into a off-duty mode in
response to said transceiver receiving no response to said at least
one ping transmission, wherein said timer is configured to be
active for a predetermined period of time when the apparatus is put
into off-duty mode, and said controller is further configured to be
inactive while said timer is active so as to avoid said apparatus
responding to wake up events while in said off-duty mode.
21. An apparatus comprising: a transceiver configured to transmit
and receive data wirelessly, a controller configured to control the
operative mode of said apparatus, a timer, and a detector
configured to detect a wake up event and to notify said controller
to put said apparatus into an operative mode if a wake up event is
detected, wherein said transceiver is further configured to
transmit at least one ping transmission, wherein said controller is
further configured to put said apparatus into a off-duty mode in
response to said transceiver receiving no response to said at least
one ping transmission, wherein said timer is configured to be
active when the apparatus is put into off-duty mode until a
predetermined time when a next duty cycle begins, and said
controller is further configured to be inactive while said timer is
active so as to avoid said apparatus responding to wake up events
while in said off-duty mode.
22. An apparatus comprising: a transceiver configured to transmit
and receive data wirelessly, a controller configured to control the
operative mode of said apparatus, a timer, and a detector
configured to detect a wake up event and to notify said controller
to put said apparatus into an operative mode if a wake up event is
detected, wherein said transceiver is further configured to
transmit at least one ping transmission, wherein said controller is
further configured to put said apparatus into a off-duty mode in
response to said transceiver receiving no response to said at least
one ping transmission, wherein said apparatus is configured to
remain in the off-duty mode, when put into the off-duty mode, until
a predetermined time representing the start of a next duty cycle,
the predetermined time being determined via use of a timer, and
said controller is further configured to be inactive while in said
off-duty mode so as to avoid said apparatus responding to wake up
events while in said off-duty mode.
23. An apparatus comprising: means controlling the operative mode
of said apparatus, means for detecting a wake up event and for
notifying said means for controlling to put said apparatus into an
operative mode in response to detecting said wake up event, means
for transmitting at least one ping transmission in response to said
apparatus being put into an operative mode, and means for notifying
said means for controlling to put said apparatus into an off-duty
mode in response to receiving no response to said at least one
transmitted advertising message; wherein said means for controlling
further comprises timer means for being active for a predetermined
period of time when the apparatus is put into an off-duty mode, and
for keeping said means for controlling inactive while said timer
means is active so as to avoid said apparatus responding to wake up
events while in said passive mode.
24. An apparatus comprising: means controlling the operative mode
of said apparatus, means for detecting a wake up event and for
notifying said means for controlling to put said apparatus into an
operative mode in response to detecting said wake up event, means
for transmitting at least one ping transmission in response to said
apparatus being put into an operative mode, and means for notifying
said means for controlling to put said apparatus into an off-duty
mode in response to receiving no response to said at least one
transmitted advertising message; wherein said means for controlling
further comprises timer means for being active when the apparatus
is put into off-duty mode until a predetermined time representing
the beginning of a next duty cycle, and for keeping said means for
controlling inactive while said timer means is active so as to
avoid said apparatus responding to wake up events while in said
passive mode.
25. An apparatus comprising a processor configured to: detect a
wake up event through a radio frequency sensor interface of said
apparatus; put said apparatus into an operative mode including
powering a radio frequency communication interface of said
apparatus and transmitting at least one ping transmission via the
radio frequency communication interface in response to detection of
said wake up event; determine whether a response to said at least
one ping transmission is received at the radio frequency interface
within a defined time frame; and put said apparatus into an
off-duty operation mode including shutting down the radio frequency
communication interface for a predetermined period of time, if no
response is received within said defined time frame, wherein in
said off-duty mode wake up events are ignored.
26. An apparatus comprising a processor configured to: detect a
wake up event through a radio frequency sensor component of said
apparatus; put said apparatus into an operative mode including
powering a radio frequency communication component of said
apparatus and transmitting at least one ping transmission via the
radio frequency communication component in response to detection of
said wake up event; determine whether a response to said at least
one ping transmission is received at the radio frequency component
within a defined time frame; and put said apparatus into an
off-duty operation mode including shutting down the radio frequency
communication component for a predetermined period of time, if no
response is received within said defined time frame, wherein in
said off-duty mode wake up events are ignored.
27. A method comprising: detecting a wake up event through a radio
frequency sensor interface of a device, putting said device into an
operative mode including powering a radio frequency communication
interface of said device and transmitting at least one
communication via the radio frequency communication interface in
response to detection of said wake up event, determining whether a
response to said at least one communication is received at the
radio frequency communication interface within a defined time
frame; and putting said device into an off-duty operation mode
including shutting down the radio frequency communication interface
until a predetermined time representing the beginning of a next
duty cycle, if no response is received within said defined time
frame, wherein in said off-duty mode wake up events are
ignored.
28. A method comprising: detecting a wake up event through a radio
frequency sensor component of a device, putting said device into an
operative mode including powering a radio frequency communication
component of said device and transmitting at least one
communication via the radio frequency communication component in
response to detection of said wake up event, determining whether a
response to said at least one communication is received at the
radio frequency communication component within a defined time
frame; and putting said device into an off-duty operation mode
including shutting down the radio frequency communication component
until a predetermined time representing the beginning of a next
duty cycle, if no response is received within said defined time
frame, wherein in said off-duty mode wake up events are
ignored.
29. An apparatus comprising a processor configured to: detect a
wake up event through a radio frequency sensor interface of said
apparatus; put said apparatus into an operative mode including
powering a radio frequency communication interface of said
apparatus and transmitting at least one communication via the radio
frequency communication interface in response to detection of said
wake up event; determine whether a response to said at least one
communication is received at the radio frequency interface within a
defined time frame; and put said apparatus into an off-duty
operation mode including shutting down the radio frequency
communication interface until a predetermined time corresponding to
the beginning of a next duty cycle, if no response is received
within said defined time frame, wherein in said off-duty mode wake
up events are ignored.
30. An apparatus comprising a processor configured to: detect a
wake up event through a radio frequency sensor component of said
apparatus; put said apparatus into an operative mode including
powering a radio frequency communication component of said
apparatus and transmitting at least one communication via the radio
frequency communication component in response to detection of said
wake up event; determine whether a response to said at least one
communication is received at the radio frequency component within a
defined time frame; and put said apparatus into an off-duty
operation mode including shutting down the radio frequency
communication component until a predetermined time representing the
beginning of a next duty cycle, if no response is received within
said defined time frame, wherein in said off-duty mode wake up
events are ignored.
31. A method comprising: detecting a wake up event through a radio
frequency sensor interface of a device, putting said device into an
operative mode including powering a radio frequency communication
interface of said device in response to detection of said wake up
event, transmitting at least one ping transmission via the radio
frequency communication interface determining whether a response to
said at least one ping transmission is received at the radio
frequency communication interface within a defined time frame; and
putting said device into an off-duty mode including shutting down
the radio frequency communication interface until a predetermined
time representing the beginning of a next duty cycle, if no
response is received within said defined time frame, wherein in
said off-duty mode wake up events are ignored.
32. A method comprising: detecting a wake up event through a radio
frequency sensor component of a device, putting said device into an
operative mode including powering a radio frequency communication
component of said device in response to detection of said wake up
event, transmitting at least one ping transmission via the radio
frequency communication component determining whether a response to
said at least one ping transmission is received at the radio
frequency communication component within a defined time frame; and
putting said device into an off-duty mode including shutting down
the radio frequency communication component until a predetermined
time representing the beginning of a next duty cycle, if no
response is received within said defined time frame, wherein in
said off-duty mode wake up events are ignored.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application claims all priority benefits under
35 U.S.C. .sctn.119 and .sctn.120 to the following, wherein the
present application is a continuation of U.S. patent application
Ser. No. 12/882,574, filed Sep. 15, 2010, pending, which '574
application published as U.S. patent application publication no. US
______, which '574 application is a continuation of U.S. patent
application Ser. No. 12/774,575, filed May 5, 2010, pending, which
'575 application published as U.S. patent application publication
no. US 2010/0214074, which '575 application is continuation of U.S.
patent application Ser. No. 12/411,205, filed Mar. 25, 2009,
pending, which '205 application published as U.S. patent
application publication no. US 2009/0181625 A1, which '205
application is a continuation of U.S. patent application Ser. No.
11/161,542, filed Aug. 8, 2005, now U.S. Pat. No. 7,522,568,
[0002] (a) which '542 application is a continuation-in-part of each
of: [0003] (1) application Ser. No. 10/604,032, filed Jun. 23,
2003, now U.S. Pat. No. 6,934,540, which published as no. US
2004/0082296, and which '032 application is a continuation-in-part
of each of, [0004] (A) application Ser. No. 09/681,282, filed Mar.
13, 2001, now U.S. Pat. No. 6,745,027, which '282 application is a
nonprovisional of application Ser. No. 60/257,637, filed Dec. 22,
2000, expired, and [0005] (B) application no. PCT/US01/49513, filed
Dec. 26, 2001, expired, designating the United States and published
in English as WO 03/032501, [0006] (i) which '513 international
application is a continuation-in-part of application Ser. No.
09/681,282, filed Mar. 13, 2001, now U.S. Pat. No. 6,745,027, which
'282 application is a nonprovisional of application Ser. No.
60/257,637, filed Dec. 22, 2000, expired, [0007] (ii) and which
'513 international application is a nonprovisional of each of
application Ser. No. 60/257,637, filed Dec. 22, 2000, and No.
60/257,398, filed Dec. 22, 2000, both expired, [0008] (2)
application Ser. No. 10/514,336, filed Nov. 12, 2004, now U.S. Pat.
No. 7,209,771, which '336 application is a national stage of
application no. PCT/US03/14987, filed May 14, 2003, expired,
designating the United States and published in English as WO
03/098851, [0009] (A) which '987 international application is a
continuation-in-part of application Ser. No. 09/681,282, filed Mar.
13, 2001, now U.S. Pat. No. 6,745,027, which '282 application is a
nonprovisional of application Ser. No. 60/257,637, filed Dec. 22,
2000, expired, [0010] (B) which '987 international application is a
continuation-in-part of application no. PCT/US01/49513, filed Dec.
26, 2001, expired, designating the United States and published in
English as WO 03/032501, [0011] (i) which '513 international
application is a continuation-in-part of application Ser. No.
09/681,282, filed Mar. 13, 2001, now U.S. Pat. No. 6,745,027, which
'282 application is a nonprovisional of application Ser. No.
60/257,637, filed Dec. 22, 2000, expired, [0012] (ii) and which
'513 international application is a nonprovisional of each of
application Ser. No. 60/257,637, filed Dec. 22, 2000, and No.
60/257,398, filed Dec. 22, 2000, both expired, [0013] (C) and which
'987 international application is a nonprovisional of each of
application Ser. No. 60/380,195, filed May 14, 2002, and No.
60/380,670, filed May 16, 2002, both expired, [0014] (b) and which
'542 application is a nonprovisional of, and claims the benefit
under 35 U.S.C. .sctn.119(e) to, each of: [0015] (1) application
Ser. No. 60/595,233, filed Jun. 16, 2005, expired, [0016] (2)
application Ser. No. 60/642,632, filed Jan. 10, 2005, expired,
[0017] (3) application Ser. No. 60/687,073, filed Jun. 3, 2005,
expired, [0018] (4) application Ser. No. 60/687,415, filed Jun. 3,
2005, expired, [0019] (5) application Ser. No. 60/688,737, filed
Jun. 8, 2005, expired, [0020] (6) application Ser. No. 60/691,574,
filed Jun. 17, 2005, expired, [0021] (7) application Ser. No.
60/691,718, filed Jun. 17, 2005, expired, [0022] (8) application
Ser. No. 60/691,884, filed Jun. 17, 2005, expired, and [0023] (9)
application Ser. No. 60/696,159, filed Jul. 1, 2005, expired.
[0024] Each of the foregoing patent applications, patents, and
patent application publications are incorporated herein by
reference.
BACKGROUND OF THE INVENTION
[0025] The present invention relates broadly to forming ad hoc
networks with radio transceivers based on common designations of
the transceivers and, in particular, to forming ad hoc networks and
distributed databases with radio transceivers in an asset-tracking
system based on asset class designations of the transceivers.
[0026] Wireless ad hoc networks allow node-to-node communication
without central control or wired infrastructure. Such networks may
have dynamic, randomly-changing, multihop topologies composed of
wireless data communication links between the nodes. Ad hoc
networks are advantageous because they are inexpensive,
fault-tolerant, and flexible. Various known methods relate to data
transmission within an ad hoc wireless data communication network.
However, most known methods do not address self-configuration of
wireless nodes for the formation and maintenance of efficient
network topology.
[0027] Known ad hoc networking methods typically organize the
network on the basis of geographic proximity of the nodes or the
strength of signals received by the various nodes. Known methods of
ad hoc network organization also require nodes to regularly
transmit network information to all other nodes in the network,
which results in increased radio traffic and interference.
Increased radio interference inhibits the formation and maintenance
of ad hoc networks having a large number of nodes and requires
nodes to transmit at a greater power, which reduces their battery
life.
[0028] Short range wireless technology such as the Bluetooth(.TM.)
radio standard promises to remove price barriers to mobile network
use. By doing so, wireless devices are becoming available for
applications where wired networks have been impracticable and in
which prior wireless communication networks have been too expensive
or inflexible. Communication between transceivers in accordance
with Bluetooth standards is at a frequency of about 2.4 GHz. While
Bluetooth radio technology is an ad hoc networking solution for
personal data applications, it provides for only a limited number
of communication channels, thereby restricting the number of
Bluetooth devices that can communicate over an ad hoc network at
any given time.
[0029] With regard to asset tracking, wireless data networks are
known for use in warehouse management and other asset-tracking
applications. However, existing wireless data network technologies
are not well suited to asset tracking, which involves a large
number of network nodes (e.g., hundreds or even thousands).
Furthermore, existing wireless technologies are cost prohibitive,
are prone to radio frequency (RF) interference, and consume a large
amount of electrical power. Accordingly, wireless data networks are
not commonly used in asset tracking.
[0030] It will therefore be apparent that needs exist: for an
improved low cost networking technology that has the benefits of
the Bluetooth price and flexibility, but that overcomes the limited
networking capacity of typical Bluetooth technology; for more
efficient methods of forming, organizing, and maintaining ad hoc
wireless networks; and for a wireless data network technology that
accommodates a large number of nodes, reduces RF interference, and
consumes less power. The present invention relates to one or more
of these needs.
SUMMARY OF THE INVENTION
[0031] Briefly described, a first aspect of the present invention
relates to a method of forming a wireless data communication
network among transceivers, wherein each transceiver includes a
designation with a first plurality of transceivers having a first
common designation and a second plurality of transceivers having a
second common designation different from the first common
designation.
[0032] In preferred embodiments, this method is used in an
asset-tracking application to form a wireless data communication
network among transceivers, wherein each transceiver includes an
asset class designation with a first plurality of transceivers
having a first class designation and a plurality of transceivers
having a second class designation different from the first class
designation. As used herein and made apparent from the following
detailed description of the present invention, an "asset" is a
person or thing that is desired to be tracked. For example, with
respect to a person, an asset may be an employee, a team member, a
law enforcement officer, or a member of the military. With respect
to an article, an asset may be, for example, a good, product,
package, item, vehicle, warehoused material, baggage, passenger
luggage, shipping container, belonging, commodity, effect,
resource, or merchandise. Similarly, as used herein and made from
the following detailed description of the present invention, an
"asset class" is a grouping of assets-whether the same or different
that share something in common, such as an attribute,
characteristic, relation, or behavior.
[0033] The method includes the steps of: forming an ad hoc
hierarchical class based network for each of the first plurality
and second plurality of transceivers; and communicating to an
external network from each transceiver of each ad hoc hierarchical
class based network. Communication to the external network from
each transceiver of each ad hoc hierarchical class based network is
accomplished by establishing a communication link between each
transceiver in a level of the ad hoc hierarchical class based
network, other than the highest level, with a transceiver in the
next higher level of the ad hoc hierarchical class based network
such that transceivers pass communications upward in the ad hoc
hierarchical class based network; and establishing a communication
link between a transceiver in the highest level of the ad hoc
hierarchical class based network and an external network access
transceiver, such that communications from transceivers in the ad
hoc hierarchical class based network are passed through the
transceiver in the highest level of the ad hoc hierarchical class
based network to the external network access transceiver.
[0034] Another aspect of the present invention relates to a method
for communicating to a recipient transceiver from a plurality of
transceivers, wherein the plurality of transceivers are located
within the broadcast range of the recipient transceiver. The method
comprising the steps of: transmitting a communication at a first
power level such that only a first group of transceivers receive
the broadcast, with the communication including a command causing
each of the first group of transceivers not to respond to a
subsequent broadcast; and subsequent thereto, transmitting a
communication at a second power level greater than the first power
level such that a second group of transceivers greater than and
including the first group of transceivers receive the broadcast,
but such that only a limited number of transceivers of the second
group respond to the broadcast. The limited number of transceivers
excludes the first group of transceivers.
[0035] In a feature of this aspect of the present invention, the
plurality of transceivers actually exceeds the number of
transceivers from which communications simultaneously can be
received by the transceiver without radio frequency interference
due to its channel capacity. In this case, the first group of
transceivers comprises a number not greater than the number of
transceivers from which communications can be received by the
transceiver without radio frequency interference due to its channel
capacity. The limited number of transceivers excludes the first
group of transceivers and also otherwise comprises a number not
greater than the number of transceivers from which communications
can be received by the transceiver without radio frequency
interference due to its channel capacity.
[0036] Yet another aspect of the present invention relates to a
method of forming a wireless data communication network among a
plurality of transceivers for tracking assets associated with the
transceivers. The method includes the steps of: assigning a class
designation to a population of transceivers based on a common
characteristic or behavior of the assets associated with the
transceivers; selecting a primary transceiver from among the
population of transceivers, the remainder of the population of
transceivers being secondary transceivers; and forming a class
based hierarchical network among the population of transceivers.
The step of forming a class based hierarchical network among the
population of transceivers itself includes: broadcasting from the
primary transceiver a primary availability signal including a
primary class identifier representative of the class designation
assigned to both the primary transceiver and the secondary
transceivers; in response to the primary availability signal,
transmitting from a responding one of the secondary transceivers a
registration signal including a secondary transceiver identifier;
storing at the primary transceiver the secondary transceiver
identifier of the responding secondary transceiver, and repeating
steps (ii) and (iii) for each of the secondary transceivers.
[0037] A fourth aspect of the present invention relates to the
forming of a wireless data communication network among a plurality
of transceivers for tracking assets associated with the
transceivers. The method includes the steps of: assigning a first
class designation to a first population of transceivers based on a
first common characteristic or behavior of the assets associated
with the first population of transceivers; assigning a second class
designation to a second population of transceivers based on a
second common characteristic or behavior of the assets associated
with the second population of transceivers; and propagating a first
and second class based hierarchical communication networks for
transmitting data among the respective first and second populations
of transceivers based on their respective class designations, the
first hierarchical communication network including a first root
primary transceiver, and the second hierarchical communication
network including a second root primary transceiver.
[0038] A fifth aspect of the present invention includes the forming
of a hierarchical ad hoc network for use in tracking assets,
comprising the steps of: identifying a first class of the assets
having a first common characteristic or behavior; identifying a
second class of the assets having a second common characteristic or
behavior; associating a wireless transceiver with each of the
assets of the first and second classes of assets, each of the
wireless transceivers including a digital processor, a memory, and
a class based network formation (CBNF) routine operable on the
digital processor; selecting a first class designation
representative of the first class of assets and a second class
designation representative of the second class of assets; storing a
first class designation in the memories of each of the wireless
transceivers associated with the first class of assets; storing a
second class designation in the memories of each of the wireless
transceivers associated with the second class of assets; and
initiating the CBNF routines of the wireless transceivers to
automatically propagate, in the absence of central control, a first
hierarchical ad hoc network among the wireless transceivers of the
first class and a second hierarchical ad hoc network among the
wireless transceivers of the second class, the first hierarchical
network being automatically organized so that it is logically
distinct from the second hierarchical network.
[0039] A sixth aspect of the present invention relates to a
portable network device adapted for attachment to one of multiple
peer assets having a common characteristic or behavior. The device
includes: a wireless transceiver; a digital information processor
in communication with the wireless transceiver; a power source for
providing electrical power to the wireless transceiver and the
digital information processor; a memory unit in communication with
the digital information processor, the memory unit adapted to store
a class designation representative of the common characteristic or
behavior; and a class based network formation (CBNF) routine
operable on the digital information processor to form a network
link selectively with one of multiple peer devices attached to
other peer assets and including a peer designation representing the
common characteristic or behavior of the peer assets, the CBNF
routine being operable to send network organization messages
including the class designation and to receive network organization
requests from the peer devices, to thereby selectively propagate a
class based hierarchical ad hoc network among the network device
and the peer devices for tracking the peer assets.
[0040] A seventh aspect of the present invention relates to a
dynamic distributed hierarchical database system for asset
tracking. The dynamic distributed hierarchical database system
includes a plurality of computer units each associated with at
least one asset having a characteristic or behavior represented by
a class designation. Each computer unit includes: a memory unit for
storing a profile representative of the class designation; an ad
hoc class based network formation routine in communication with the
memory for establishing a hierarchical network with other computer
units based on the class designation; and a query handling routine
for interpreting and responding to database queries received from
an asset-tracking application that correspond to the class
designation.
BRIEF DESCRIPTION OF THE DRAWINGS
[0041] Further aspects, feature, benefits, and advantages of the
present invention will be apparent from a detailed description of
preferred embodiments thereof taken in conjunction with the
following drawings, wherein similar elements are referred to with
similar reference numbers, and wherein:
[0042] FIG. 1 illustrates various network components and an example
arrangement in the context of a warehouse application in accordance
with the present invention;
[0043] FIG. 2 is a flowchart illustrating a preferred operation of
the CBNF routine operating on Wireless Reader Tags in accordance
with the present invention;
[0044] FIGS. 3-11 illustrate a time sequence that depicts Wireless
Reader Tags of arbitrary classes "circle" and "triangle,"
transmitting a series of messages in the course of self-organizing
a hierarchical network using a bottom-up propagation approach;
[0045] FIGS. 6A, 8A, 9A, 10A, and 11A illustrate the topology of
the ad hoc network formed at the stages depicted in corresponding
FIGS. 6, 8, 9, 10, and 11, respectively;
[0046] FIGS. 12-21A illustrate a time sequence of ad hoc net work
formation using a top-down propagation approach;
[0047] FIG. 22 illustrates a step-power filtering routine utilized
by a Wireless Reader Tag in accordance with the present invention;
and
[0048] FIGS. 23 and 24 illustrate, respectively, Tables 1 and 2
discussed below.
DETAILED DESCRIPTION
[0049] As a preliminary matter, it will readily be understood by
one having ordinary skill in the relevant art ("Ordinary Artisan")
that the present invention has broad utility and application.
Furthermore, any embodiment discussed and identified as being
"preferred" is considered to be part of a best mode contemplated
for carrying out the present invention. Other embodiments also may
be discussed for additional illustrative purposes in providing a
full and enabling disclosure of the present invention. As should be
understood, any embodiment may incorporate only one or a plurality
of the above-disclosed aspects of the invention and may further
incorporate only one or a plurality of the above-disclosed
features. Moreover, many embodiments, such as adaptations,
variations, modifications, and equivalent arrangements, will be
implicitly disclosed by the embodiments described herein and fall
within the scope of the present invention.
[0050] As a preliminary matter, it will readily be understood by
those persons skilled in the art that the present invention is
susceptible of broad utility and application in view of the
following detailed description of the preferred devices and methods
of the present invention. Many devices, methods, embodiments, and
adaptations of the present invention other than those herein
described, as well as many variations, modifications, and
equivalent arrangements, will be apparent from or reasonably
suggested by the present invention and the following detailed
description thereof, without departing from the substance or scope
of the present invention. Accordingly, while the present invention
is described herein in detail in relation to preferred devices,
methods and systems, it is to be understood that this disclosure is
illustrative and exemplary and is made merely for purposes of
providing a full and enabling disclosure of the preferred
embodiments of the invention. The disclosure herein is not intended
nor is to be construed to limit the present invention or otherwise
to exclude any such other embodiments, adaptations, variations,
modifications and equivalent arrangements, the present invention
being limited only by the claims appended hereto and the
equivalents thereof.
[0051] Preferred embodiments of the present invention relate to
asset tracking. In particular, each asset to be tracked is tagged
with a wireless transceiver (hereinafter referred to as a "Wireless
Tag" or "WT") and reading the Wireless Tag using another wireless
transceiver (hereinafter referred to as a "Wireless Reader Tag" or
"WRT").
[0052] The Wireless Tag itself preferably is semi-passive, although
a passive, active, or other type of Wireless Tag could be used
within the scope of the present invention. The Wireless Reader Tag
itself preferable is active. A passive transceiver receives and
transmits primarily using inductive energy. A semi-passive
transceiver receives primarily using inductive energy and transmits
using internally stored energy, such as battery. An active
transceiver receives and transmits using internally stored energy,
such as a battery.
[0053] In the preferred embodiments, the Wireless Tags are
radio-frequency transponders ("RFTs") and the Wireless Reader Tags
are low-power radio frequency ("LPRF") devices. As used herein, the
term "LPRF" refers generally to a two-way wireless radio-frequency
data communication device that transmits data in packets, and is
not limited to a particular signal strength or power
consumption.
[0054] Each Wireless Tag includes a unique identification
(hereinafter "WT ID") stored therein that uniquely identifies the
Wireless Tag in transmissions made by the Wireless Tag and,
likewise, each Wireless Reader Tag includes a unique identification
(hereinafter "WRT ID") stored therein that uniquely identifies the
Wireless Reader Tag in transmissions made by the Wireless Reader
Tag.
[0055] The Wireless Reader Tags preferably operate in accordance
with the Bluetooth.TM. standards, which is a wireless radio
specification. However, it should be understood that the invention
is not limited to use with Bluetooth.TM. technology, but can be
used with any wireless transceiver having the capability to
communicate directly with other wireless transceivers, such as
wireless Ethernet transceivers, 802.11, Home RF, and others.
[0056] In accordance with the present invention, each Wireless Tag
also includes, apart from its WT ID, a "class designation"
representative of an attribute, characteristic, relation, or
behavior of the asset (and not the Wireless Tag itself, and each
Wireless Tag is said to belong to, or be a member of, a particular
WT Class based on its class designation. Identification of the WT
Class for which a particular Wireless Tag is designated preferably
is stored on the Wireless Tag and is utilized by the Wireless Tag
in screening broadcasts for determining whether to respond thereto
with a transmission.
[0057] The WT Class may represent any type of identification, as
desired. For instance, a particular WT Class could represent a
category of an asset, such as a ball (identified by/ball); a
subcategory such as a soccer ball (identified by /soccer_ball); or
a subcategory of the subcategory (a sub-subcategory), such as a
size 5 soccer ball (identified by/size_5_soccer_ball). When the WT
Class represents a subcategory or sub-category, for example, the WT
Class may also represent the category or subcategory, respectively,
abstracted from the subcategory or sub-category. Thus, a WT Class
representing a sub-subcategory equal to
/ball/soccer_ball/size_5_soccer_ball also inherently identifies a
subcategory (soccer_ball) and a category (ball). Alternatively, the
a WT Class may be intentionally limited to identification only of
the sub-subcategory (/size_5_soccer_ball). If so limited,
additional information inferred from this identification about the
subcategory and/or category of such WT Class then may be maintained
in memory on the Wireless Reader Tag (described below) or remotely
in category dictionaries or category rule sets.
[0058] When a broadcast or multicast is made to the Wireless Tags
(hereinafter "WT Broadcast"), each Wireless Tag is capable of
identifying a specified WT Class in the WT Broadcast and replying
to the WT Broadcast with its own transmission when the specified WT
Class matches its WT Class. If the WT Class does not match its
class designation, then the Wireless Tag does not respond to the WT
Broadcast and it makes no transmission. In this regard, each
Wireless Tag is a transponder that may be selectively activated.
Semi-passive transceivers that are capable of being used to respond
to targeted broadcasts in accordance with the present invention,
and not to every broadcast received, are well known within the art
and, accordingly, the specific design of such semi-passive
transceivers forms no part of the present invention.
[0059] Each Wireless Reader Tag also includes a class designation,
and each Wireless Reader Tag is said to belong to, or be a member
of, a WRT Class. Preferably each Wireless Reader Tag is associated
with at least one WT Class for reading Wireless Tags that are
members thereof. In this regard, the Wireless Reader Tag
communicates with (or "reads") those Wireless Tags having a WT
Class with which it is associated by making a WT Broadcast
specifying the WT Class in the transmission. The identification of
associated WT Classes of a Wireless Reader Tag preferably is
preprogrammed into the memory of, or otherwise maintained in, the
Wireless Reader Tag. Active transceivers that are capable of being
used to make broadcasts that identify targeted semi-passive
transceivers for response are well known within the art and,
accordingly, the specific design of such active transceivers forms
no part of the present invention. Preferably, however, each
Wireless Reader Tag includes a digital processor and memory for
storing the WRT Class thereof and associated WT Classes, the
members of which are to be read by the Wireless Reader Tag.
[0060] In one aspect of the invention, a class adoption step is
also utilized in which a WRT Class is adopted by a Wireless Reader
Tag that is detected as being the WRT Class of a nearby Wireless
Reader Tag, or that is associated with a detected WT Class of a
nearby Wireless Tag. Typically, such class adoption is performed
only when the adopting Wireless Reader Tag is unable to participate
in the ad hoc hierarchical network formation because of a missing
or corrupted class designation. Moreover, in some circumstances
such a class adoption step may be useful even if the adopting
Wireless Reader Tag has sufficient class designation information to
support communication. For example, a Wireless Reader Tag attached
to a pallet could periodically update its class designation by
detecting the WRT Classes of nearby Wireless Reader Tags and the
corresponding WT Classes of nearby Wireless Tags (e.g., those
attached to items placed on a pallet). Alternatively a Wireless
Reader Tag can be manually programmed with a class designation by
use of a handheld communicator (hereinafter "Communicator"). The
Communicator is a sort of remote control device that allows a human
operator to program Wireless Reader Tags and to query Wireless
Tags. Preferably, the Communicator includes a LPRF device that is
controlled by application software designed to facilitate manual
human interaction and communication with nearby Wireless Reader
Tags and Wireless Tags. In preferred embodiments, the Communicator
comprises a PDA, such as those available from Handspring Inc. or
Palm Corp., that is appropriately configured for use with the
present invention.
[0061] In reading Wireless Tags, a Wireless Reader Tag is capable
of communicating with a limited number of Wireless Tags at any
given time. Accordingly, if a large number of Wireless Tags are to
be read by a particular Wireless Reader Tag, the Wireless Tags are
read using a step-power filtering routine in accordance with the
present invention. In this regard, a Wireless Reader Tag is capable
of transmitting at different power levels. By transmitting a
different consecutive power levels, a Wireless Reader Tag may read
a large number of Wireless Tags that otherwise would not be read
due to RF interference.
[0062] With reference to FIG. 22, a Wireless Reader Tag "M" is
shown spaced at different distances to Wireless Tags S1,S2,S3,S4.
In accordance with the step-power filtering routine, the Wireless
Reader Tag broadcasts at a first power level 10 a transmission
specifying the WT Class of all of the illustrated Wireless Tags S.
The broadcast is received by the closest three Wireless Tags shown
within the inner circle 1010, which represents the effective
transmission range of the Wireless Reader Tag at the first power
level. The broadcast includes, inter alia, a command to ignore
subsequent transmission specifying the same WT Class within a
predetermined time period thereafter. The Wireless Tags receiving
this transmission then respond appropriately and power down for the
predetermined time period.
[0063] Next, the Wireless Reader Tag broadcasts at a second,
stronger power level 20 a transmission specifying the same WT
Class. The broadcast is received by the closest six Wireless Tags
shown within the inner circle 2020, which represents the effective
transmission range of the Wireless Reader Tag at the second power
level. The broadcast includes, inter alia, a command to ignore
subsequent transmission specifying the same WT Class within a
predetermined time period thereafter. The three outermost Wireless
Tags S2 receive this transmission, respond appropriately, and then
power down for the predetermined time period. The innermost
Wireless Tags S1 do not respond, as each has previously been
instructed to ignore this subsequent transmission.
[0064] This process then repeat two more times, whereby all fifteen
Wireless Tags have been read. Specifically, the Wireless Reader Tag
next broadcasts at a third, stronger power level 30 a transmission
specifying the same WT Class. The broadcast is received by the
closest eleven Wireless Tags shown within the inner circle 3030,
which represents the effective transmission range of the Wireless
Reader Tag at the third power level. The broadcast includes, inter
alia, a command to ignore subsequent transmission specifying the
same WT Class within a predetermined time period thereafter. The
five outermost Wireless Tags S3 receive this transmission, respond
appropriately, and then power down for the predetermined time
period. The innermost Wireless Tags S1,S2 do not respond, as each
has previously been instructed to ignore this subsequent
transmission.
[0065] Finally, the Wireless Reader Tag next broadcasts at a
fourth, yet stronger power level 40 a transmission specifying the
same WT Class. The broadcast is received by all Wireless Tags shown
within the inner circle 4040, which represents the effective
transmission range of the Wireless Reader Tag at the fourth power
level. The broadcast includes, inter alia, a command to ignore
subsequent transmission specifying the same WT Class within a
predetermined time period thereafter. The four outermost Wireless
Tags S4 receive this transmission, respond appropriately, and then
power down for the predetermined time period. The innermost
Wireless Tags S1,S2,S3 do not respond, as each has previously been
instructed to ignore this subsequent transmission. In an
alternative step-power filtering technique, the power level of the
broadcast is included in the transmission. Then, as each Wireless
Tag receives the broadcast, the power level is noted and a range
thereof is used with the WT Class for prescreening of further
transmissions. In this regard, only those transmissions falling
within the predetermined range about the power level of the
broadcast are received and processed by the particular Wireless
Tags. Thereafter, a "reset" command is broadcast to all of the
Wireless Tags in order to enable receipt thereafter of a broadcast
at any power level, or alternatively, the power level screening is
dropped after a predetermined time period.
[0066] The WRT class designations primarily are used by Wire 10
less Reader Tag to screen each broadcast or multicast intended for
receipt by a particular class of Wireless Reader Tags (hereinafter
"WRT Broadcast"). Typically, a command, query, or the like
(generically referred to as a message) is communicated in a
transmission to members of a WRT Class in a WRT Broadcast as part
of a data packet that begins with a preamble including an
identification of the WRT Class intended as the target of the
broadcast. Other information may also be included in the data
packet for screening purposes by each Wireless Reader Tag. Wireless
Reader Tags within range of the WRT Broadcast awake from a standby
mode to receive the data packet, but only process the message
therein with possible transmissions in response thereto when the
WRT Class of the preamble matches the WRT Class of the Wireless
Reader Tag (and when the other screening information, if present,
also is matched). If there is no match, then the particular
Wireless Reader Tag does not process the message, drops the data
packet, and returns to standby mode.
[0067] A Wireless Reader Tag or a Wireless Tag also may store in
memory additional information such as: sensor derived information
(e.g., temperature, humidity, altitude, pressure); a priority
designation to provide improved response to selected broadcasts; a
privilege level (e.g., "visitor," "employee," "manager,"
"administrator," and "super user"); time-sensitive information
(e.g., synchronization timing, real-time sensor data, and GPS
data); a characteristic of the particular tagged asset (e.g.,
serial number, status, process step, physical location, color,
size, density); and/or a behavior of the tagged asset (e.g.,
temperature sensitivity, light sensitivity, shelf life). A Wireless
Reader Tag also may store a WRT rank in a hierarchical ad hoc
network formed by the Wireless Reader Tags (e.g., "primary" or
"master," "secondary" or "slave," "sub-primary," "tertiary");
and/or an identification of the WT Class for which a particular
Wireless 45 Tag is designated, indexed by WT ID for the particular
Wireless Tag, especially if the Wireless Tag can store only the WT
ID (e.g., when the Wireless Tag is passive).
[0068] In further accordance with the present invention, each of
the Wireless Reader Tags also includes a class based network
formation (CBNF) routine that enables the Wireless Reader Tags to
coordinate with one another in collectively forming hierarchical ad
hoc networks, each network being defined by Wireless Reader Tags of
a common WRT Class (hereinafter "Class Based Network"). The CBNF
routine is executed upon startup of the Wireless Reader Tag, on
specific command broadcast to the Wireless Reader Tag, or as
otherwise needed (such as to maintain an ad hoc network). The CBNF
routine is implemented in software operable on the digital
processor of each Wireless Reader Tag in the preferred embodiments.
Alternatively, the CBNF routine is implemented in other ways, such
as hardwired logic circuitry in each of the Wireless Reader Tags.
As described in detail below, each Class Based Network is a
hierarchical network that provides an efficient topology for
selective communication among Wireless Reader Tags of the same WRT
Class.
[0069] WRT Broadcasts are made by a network interface module
(hereinafter "Gateway") that serves as a communication link between
the ad hoc hierarchical networks established by the Wireless Reader
Tags and an external network, such as a local area network (LAN),
wide area network (WAN), or the Internet. The Gateway includes at
least a network interface and an RF interface for communication
with Wireless Reader Tags of the ad hoc networks. An asset-tracking
application server or equivalent computer system is connected with
the external network and obtains through the ad hoc networks
information on the tagged assets for compilation, analysis, and/or
display.
[0070] Communication between the Gateway and a Wireless Reader Tag
of the highest hierarchical level in each Class Based Network may
be established utilizing step-power filtering technique if a number
of Class Based Networks otherwise exceeds the multiple channel
communication capabilities of the Gateway. In this respect, the
Gateway is enabled to selectively communicate with such Wireless
Reader Tags based on physical distance from the Gateway.
[0071] Application Server communicates with nodes of ad hoc network
the external network and the Gateway to obtain and compile
information regarding tagged assets. In this respect, it now will
be appreciated by those having ordinary skill in the art that the
nodes of these Class Based Networks comprise a distributed database
of information pertaining to the tagged assets. As set forth above,
a Wireless Reader Tag or a Wireless Tag stores in memory not only a
WRT ID or WT ID, respectively, but also may store additional
information such as, for example: class designation; sensor derived
information; a priority designation to provide improved response to
selected broadcasts; a privilege level; timesensitive information;
a characteristic of the particular tagged asset; and/or a behavior
of the tagged asset. This stored information becomes accessible by
the tracking application server through the Classed Based Networks.
The asset-tracking application server also can obtain the WRT ID
associated with each WT ID for intelligence gathering purposes.
[0072] Turning now to FIG. 1, a preferred embodiment of the present
invention is illustrated in a shipping environment 100 including a
warehouse 104. A Wireless Reader Tag 110 (also represented by
"LPRF" in the drawings) is attached to each pallet 120 in the
shipping environment 100. An actual implementation would involve
thousands of pallets and LPRFs; however, for clarity only three
pallets 120 and Wireless Reader Tags 110 are shown in FIG. 1.
Assets 134 on the pallets 120 each are tagged with a Wireless Tag
130 (also represented by "RFT" in the drawings).
[0073] Each Wireless Reader Tag 110 preferably is active, while
each Wireless Tag 130 preferably is semi-passive. As set forth
above, passive Wireless Tags 110 and Wireless Reader Tags 130 are
devices that collect RF energy inductively and selectively respond,
including sending information that is stored thereon. These type of
devices may be viewed as selective reflectors of incident RF
signals. Semi-passive and semi-active Wireless Tags 110 and
Wireless Reader Tags 130 are devices that use internal energy, in
the form of a battery, to power some portion of the circuit to
either detect a transmission or make a transmission. Active
Wireless Tags 110 and Wireless Reader Tags 130 are devices that use
internal power, in the form of a battery, to both detect and make
transmissions.
[0074] Preferably, both Wireless Tags 130 and Wireless Reader Tag
110 are read-write devices, but the Wireless Tags 130 may be
read-only (generally characteristic of passive devices) within the
scope of the present invention.
[0075] A Gateway 140 (also represented by "NIM" in the drawings)
represents a communication link between an external network (LAN)
150 and Class Based Networks formed by the Wireless Reader Tags
110. The Gateway 140 is an external network access transceiver that
comprises a radio base station directly or indirectly connected to
a wired network (e.g., using Ethernet, or wireless Ethernet). The
radio base station portion of Gateway 140 is an LPRF compatible
module that communicates with Wireless Reader Tags 110 of the Class
Based Networks. In essence, the Gateway 140 links the Class Based
Network of the present invention with conventional network
topologies that use conventional network protocols. The Gateway 140
thereby facilitates monitoring, controlling, and querying Wireless
Reader Tags 110 and Wireless Tags 130 in the Class Based Networks
using application software running on a server computer 160
connected to the external network 150. The server 160 may be
operated on a general purpose computer, such as a personal
computer, minicomputer, or mainframe.
[0076] A system in accordance with the present invention may
include components in addition to those described above. For
example, a Communicator 170 (also represented by "HIM" in the
drawings) and a mobile locating Gateway 180 (also represented by
"MLG" in the drawings) are provided in the preferred embodiment of
FIG. 1. Communicator 170 is used to manually read class
designations from network entities, such as Wireless Reader Tag 110
and Wireless Tags 130, and to assign class designations. Gateway
180, which is installed in shipping vehicle 184, has the core
capabilities of a Wireless Reader Tag and a Gateway, plus at least
two additional features. Gateway 180 includes a GPS receiver (not
depicted) for determining geographic location of shipping vehicle
184 and a mobile interface such as a cellular or satellite
transmitter 186 for transmitting data to server computer 160 via a
mobile phone network 188. In implementation, the Communicator 170
and Gateway 140,180 each include a Wireless Reader Tag incorporated
therein. Thus, because Gateway 140,180 and Communicator 170 each
includes the core hardware and software of a Wireless Reader Tag,
each can actively participate in the formation, control, and
maintenance of the Class Based Networks.
[0077] The operation of the CBNF routine of multiple Wireless
Reader Tags in accordance with the present invention for forming
Class Based Networks now is described.
[0078] Network Formation
[0079] In accordance with the present invention, the CBNF routines
of multiple Wireless Reader Tags cooperate to propagate a distinct
hierarchical network among each of multiple WRT Classes of the
Wireless Reader Tags. To accomplish this class based network
formation, the WRT Class for each Wireless Reader Tag is stored in
memory and included in the preamble of each network formation
communication generated by the Wireless Reader Tag. The WRT Class
may be identified by any series of codes or characters, the
interpretation of which should be standardized and used by all
possible recipients of network formation communications (including
all Wireless Reader Tags 110, Gateways 140,180, and Communicator
170). For example, a WRT Class may include a category/subcategory
list such as "/Wal-Mart/Shipment_123", or a linked list
representing relationships of various categories and subcategories
defined in a profile of the Wireless Reader Tag. Moreover, in this
example, the WT Classes of Wireless Tags associated with a Wireless
Reader Tag of the WRT Class "/Wal-Mart/Store_290/Shipment 123"
could include "/Televisions/32in" and "/Televisions/27in",
representing 32 inch televisions and televisions 27 inch
televisions on a pallet (to which the Wireless Reader Tag is
attached) that is scheduled for inclusion with shipment number 123
to Wal-Mart store number 290.
[0080] Alternatively, if Wireless Reader Tags 110 are not
preprogrammed in non-volatile read/write memory with a WRT Class
designation, a Wireless Reader Tag 110 may acquire a class
designation by reading Wireless Reader Tags 110 or Wireless Tags
130 nearest to it, and then store the class designation and other
profile information in non-volatile read/write memory. Thus, when a
pallet 120 is moved onto shipping vehicle 184, the pallet's
Wireless Reader Tag 110 migrates to join a Class Based Network
headed by Gateway 180. Gateway 180 is then able to report the
migration to server 160 via a network link that it has formed with
Gateway 140.
[0081] In accordance with the present invention, the CBNF routines
of multiple Wireless Reader Tags cooperate to propagate a distinct
hierarchical network among each of multiple WRT Classes of the
Wireless Reader Tags. To accomplish this class based network
formation, the WRT Class for each Wireless Reader Tag is stored in
memory and included in the preamble of each network formation
communication generated by the Wireless Reader Tag. The WRT Class
may be identified by any series of codes or characters, the
interpretation of which should be standardized and used by all
possible recipients of network formation communications (including
all Wireless Reader Tags 110, Gateways 140,180, and Communicator
170). For example, a WRT Class may include a category/subcategory
list such as "/Wal-Mart/Shipment_123", or a linked list
representing relationships of various categories and subcategories
defined in a profile of the Wireless Reader Tag. Moreover, in this
example, the WT Classes of Wireless Tags associated with a Wireless
Reader Tag of the WRT Class "/WalMart/Store_290/Shipment_123" could
include "/Televisions/32in" and "/Televisions/27in", representing
32 inch televisions and televisions 27 inch televisions on a pallet
(to which the Wireless Reader Tag is attached) that is scheduled
for inclusion with shipment number 123 to Wal-Mart store number
290.
[0082] Alternatively, if Wireless Reader Tags 110 are not
preprogrammed in non-volatile read/write memory with a WRT Class
designation, a Wireless Reader Tag 110 may acquire a class
designation by reading Wireless Reader Tags 110 or Wireless Tags
130 nearest to it, and then store the class designation and other
profile information in non-volatile read/write memory.
Specifically, a WRT can acquire or "adopt" a class designation from
a surrounding WRT or WT when that function is provided for in the
"profile" of the WRT. As used herein, a "profile" of a WRT includes
a list of attributes that invoke operating system functions, and
can include information such as "adopted class." If, for example, a
WRT that is in a manufacturing area moves past a physical boundary
that puts it within a shipping area, then the WRT automatically
adopts a shipping class for its previous manufacturing class. The
class designations may look like this:
[0083] When in Manufacturing:
/Sony/TV/24''/ManufacturingFinishing/Serial #10
[0084] When in Shipping: /Sony/TV/24''/Shipping/Serial #10
[0085] The value to this system is that as products are completed,
the class on a pallet will not need to be manually changed because
it automatically updates according to location (i.e., near the
shipping docks). The same may happen once a driver leaves the
parking lot and the radios no longer communicate to a NIM, but now
communicate with a MLG. In this case, the class designations may
look like this:
[0086] /Sony/TV/24''/Intransit/ABC Trucking/Serial #10
[0087] Thus, when a pallet 120 is moved onto shipping vehicle 184,
the pallet's Wireless Reader Tag 110 migrates to join a Class Based
Network headed by Gateway 180. Gateway 180 then is able to report
the migration to application server 160 via a network link that it
has formed with Gateway 140.
[0088] The WRT Class may also include other information concerning
a status, characteristic, or privilege of the Wireless Reader Tag,
the network, or other conditions. Virtually any profile information
can be included in the preamble and combined with class designation
information to be used for network formation. Furthermore, the
preamble information can be represented in any convenient format,
including various encoding schemes. In one embodiment, a Walsh code
is assigned to each class definition and provided to Wireless
Reader Tags of the class.
[0089] Walsh codes are well understood in the field of digital
wireless communications and, therefore, require only a brief
explanation here. Walsh codes are used to encode data packets and
to designate the class of Wireless Reader Tags that are enabled to
receive and decode a particular packet of data. The association of
Walsh codes with class designation information facilitates reduced
battery consumption in Wireless Reader Tags by utilizing targeting
methods requiring very little processing power. The use of Walsh
codes also improves data security by encoding of such
communications. Those skilled in the art will recognize that many
other methods may be used for encoding class designation
information in the preamble of data packets to facilitate class
based network formation and network formation communications while
reducing battery consumption and RF interference.
[0090] FIG. 2 is a flowchart illustrating a preferred operation of
the CBNF routine in accordance with the present invention to form a
Class Based Network. With reference to FIG. 2, upon power up, a
first Wireless Reader Tag of a predetermined WRT Class initially
listens (Step 210) for transmissions of other Wireless Reader Tags
of the same WRT Class, which would indicate the presence of a Class
Based Network for such WRT Class. If such a Class Based Network is
detected, then the first Wireless Reader Tag attempts to join (Step
220) the Class Based Network as a "secondary" unit by issuing a
registration request signal. Otherwise, if no Class Based Network
is detected, then the first Wireless Reader Tag attempts join the
overall network by establishing such a Class Based Network as a
"primary" unit. This is done by transmitting (Step 230) a
"primary_ready" signal to all other Wireless Reader Tags of the
same WRT Class within the broadcast range of the first Wireless
Reader Tag. The first Wireless Reader Tag then listens (Step 240)
for replies from other Wireless Reader Tags attempting to register
as secondary units in the new Class Based Network.
[0091] If no reply for registration as a secondary unit is
detected, and if the WRT Class of the first Wireless Reader Tag can
be abstracted, then the WRT Class is abstracted (Step 250) by
truncating the class designation. For example, if the initial WRT
Class is "/WalMart/Store_290/Shipment_123", then the class
designation is abstracted to "/Wal-Mart/Store_290". The process
then repeats starting at Step 210 for this abstracted class
designation as the new WRT Class for the first Wireless Reader Tag.
If this process continues to repeat, the class designation will not
be able to be abstracted further without otherwise being generic to
all classes of Wireless Reader Tags, i.e., WRT Class being "/". At
this point, the first Wireless Reader Tag attempts to connect (Step
294) to a Gateway ("NIM" in FIG. 2) and register as a member of the
WRT Class that is the highest abstraction possible without being
generic to all Wireless Reader Tags (i.e., as a member of the root
class "/Wal-Mart"). Upon successful registration with the Gateway,
the first Wireless Reader Tag then enters (Step 296) sleep-or sleep
or standby-mode to conserve battery power.
[0092] If a reply from a secondary unit is detected, then the first
Wireless Reader Tag registers (Step 260) the secondary unit and
repeats the registration for each reply from other secondary units
until a determination is made (Step 270) or until no more such
replies are detected. A "cluster" in this context comprises a
primary unit and the secondary units with which the primary
communicates directly, and may be limited in number of units by the
number of communication channels that can be supported by the
primary unit operating as a cluster head. Once a cluster is full,
the first unit (cluster head) responds to the next secondary unit
attempting to register by promoting (Step 280) it to the status of
a primary unit. The first Wireless Reader Tag-now the cluster head
of the full cluster-then attempts to register (Step 290) with the
newly promoted primary unit as one of its secondary units. The new
primary unit, in turn, then is available to serve as a cluster head
for other Wireless Reader Tags, to promote other Wireless Reader
Tags to higher level primary units, and so forth, thereby
propagating a hierarchical Class Based Network from the
"bottom-up." The first Wireless Reader Tag and the other Wireless
Reader Tags form the Class Based Network using the same CBNF
routine.
[0093] Returning to Step 270, if the cluster of the first Wireless
Reader Tag does not completely fill, if no more first Wireless
Reader Tags attempt to register as secondary units, and if the
first Wireless Reader Tag has a class designation that is other
than its root class, then the first Wireless Reader Tags abstracts
its WRT Class (Step 250) by truncating the class designation and
starts over the entire CBNF routine beginning at Step 210 (i.e.,
listening for the presence of Wireless Reader Tags of the truncated
class at Step 210, etc.). Note that in accordance with preferred
embodiments of the present invention, a Wireless Tag or Wireless
Reader Tag will respond if its class is identified in a
communication, even if the class in the communication is
abstracted. Thus, a Wireless Tag or a Wireless Reader Tag having a
class designation of "/sony/tv/color/24" will respond to a
communication identifying the class as "/sony/tv" as its class
(i.e., its abstracted class) is identified in the
communication.
[0094] If no other Wireless Reader Tags are attempting to register
and if the first Wireless Reader Tag's WRT Class cannot be
abstracted, then the first Wireless Reader Tag attempts to register
(Step 294) with the Gateway and, thereafter, enters (Step 296) into
an idle mode. Alternatively, the first Wireless Reader Tag may
start attempting to register with the Gateway soon after it becomes
a primary at Step 230 or concurrently with filling its cluster at
Step 270. Furthermore, when promoting a Wireless Reader Tag to a
primary unit, the first Wireless Reader Tag would also pass to the
promoted Wireless Reader Tag the responsibility for connecting with
the Gateway on behalf of the cluster, possible.
[0095] In accordance with the Bluetooth standard, the Gateway will
be able to communicate with seven other WRTs simultaneously.
However, the targeted WRT Class can revolve on each channel as a
function of time in order to address multiple WRT Classes on the
single channel. Upon registration with the Gateway, the system may
establish a revolving communication schedule with revolving class
addressing that allows the Gateway to communicate with hundreds or
thousands of WRT Classes on the channel. Synchronization between
the Gateway and Wireless Reader Tags is important for proper
operation of revolving class addressing and to minimize battery
consumption. Accordingly, as WRT Classes are added to the overall
network and establish communication with a Gateway, the Gateway may
synchronize, reconfigure, and optimize the WRT Class' schedule for
revolving class addressing.
[0096] The Class Based Networks also are reconfigurable in response
to changes in the location, status, behavior, characteristics or
class designation associated with the Wireless Reader Tags. For
example, assets of a class (e.g., in-production) can be selectively
transferred to a new class (e.g., shipping) by merely changing the
WRT Class designation with which the assets are associated. Class
Based Networks also facilitate the use of asset-tracking
applications and process flow controls to track and manage the
assets based on real-world requirements, such as manufacturing
requirements, shipment, warehouse management, zone control,
environmental impacts, etc. Class Based Networks also facilitate
automated segregation and delivery of assets.
[0097] In a "top-down" CBNF routine, illustrated in FIGS. 12-21,
when a cluster is filled the secondary units that have already
registered with the first Wireless Reader Tag (the cluster head)
may be promoted to assume the role of middle-hierarchy primary
units, called "sub-primaries." Sub-primaries, which continue as
secondary units below the first Wireless Reader Tag (cluster head),
then provide connectivity for any additional Wireless Reader Tags
that are attempting to join the Class Based Network in clusters
headed by the sub-primaries.
[0098] In both the top-down and bottom-up methods, secondary units
promoted by the first Wireless Reader Tag become new cluster heads
that, themselves, may provide connectivity to Wireless Reader Tags
of the same WRT Class that are beyond the actual transmission range
of the first Wireless Reader Tag. The Wireless Reader Tags thereby
collectively form a hierarchical, multi-tiered network based on
class designation that propagates both in quantity of nodes and
geographic coverage. Tightly grouped Class Based Networks formed in
accordance with the present invention thus make it possible to
communicate to and among a particular target class of Wireless
Reader Tags without requiring messages to be received, processed,
or routed by Wireless Reader Tags that are not members of the
target WRT Class or an abstracted Class thereof. This hierarchical
Class Based Networks is an efficient topology for communicating
among Wireless Reader Tags of the same WRT Class, because it
reduces the number of network nodes through which messages must
pass and, consequently, thereby significantly reduces RF
interference and battery power consumption otherwise
experienced.
[0099] FIGS. 3-11 depict Wireless Reader Tags in a time-sequence of
events showing a bottom-up method of the CBNF routine. With
reference to FIGS. 3-11, Wireless Reader Tags 1-6 and Wireless
Reader Tags A-G are members of WRT Classes "circle" and "triangle,"
respectively, which are arbitrary class designations assigned for
purposes of illustration only. In this example, the Wireless Reader
60 Tags 1-6 and Wireless Reader Tags A-G operate on up to three
communication channels and one general channel (also called the
control channel). The Wireless Reader Tags all include CBNF
routines operating in accordance with the method shown in FIG.
2.
[0100] The CBNF routine of each Wireless Reader Tags 1-6 and
Wireless Reader Tags A-G is configured to initially listen for a
communication having a data packet with a preamble that identifies
a Wireless Reader Tag of the same WRT Class as the Wireless Reader
Tag executing the CBNF routine (see FIG. 2, Step 210). In this
example, the preamble of each packet is represented by a
colon-separated string of information, as follows:
[0101] Target Class: My Profile: Action Requested: Target Cluster
Head ID
[0102] where "Target Class" is the WRT Class of Wireless Reader
Tags directed to wake up from standby to receive and process the
data packet. In this example, the Target Class is either "/circle"
or "/triangle" (there are no subcategories in this example).
However, in a more complex embodiment (not shown) the Target Class
designation could include subcategory information in a
slash-separated list, in a linked list, with Walsh codes, or by any
other method of representing category and subcategory information.
The "My Profile" section of the preamble identifies the Wireless
Reader Tag transmitting the communication by WRT Class and WRT ID
unique to the Wireless Reader Tag. The "Action Requested" includes
the message, and the "Target Cluster Head ID" identifies the
Wireless Reader Tag of the cluster head or proposed cluster head,
if any.
[0103] Thus, for example, with reference to FIG. 3, after listening
for data packets of its WRT Class (i.e., /circle) and detecting
none, Wireless Reader Tag 1 attempts to start a Class Based Network
for the WRT Class of "/circle" as a primary unit by transmitting a
data packet having the following preamble:
[0104] :/circle:/circle/unit 1:primary_ready:no_primary
[0105] The class designation "/circle" causes only Wireless Reader
Tags of the WRT Class "/circle" to receive and process the message
of the data packet. Wireless Reader Tag 1, if it receives no
replies, may retransmit the communication multiple times before
timing out and beginning a beacon procedure or entering a
battery-saving lost mode. Furthermore, the data packets (and others
described below) may encapsulate a data payload or may have a null
payload.
[0106] Wireless Reader Tags are preferably synchronized to allow
scheduled communication to a particular WRT Class at regular
intervals. When an Wireless Reader Tag communicates to a target WRT
Class, the Wireless Reader Tag transmits a data packet at a time
precisely synchronized with the targeted WRT Class. To conserve
battery power, the receiving members of the WRT Class only power up
to listen at each such interval and only for very small periods of
time (e.g., a few milliseconds) when data packet for such WRT Class
would normally be transmitted. The intervals at which a Wireless
Reader Tag listens for communications directed to its WRT Class is
called the duty cycle, which can be dynamically adjusted to respond
to network communication demands while minimizing battery
consumption. Depending upon the time sensitive nature of the assets
being tracked and their priority, a period of inactivity may prompt
a Wireless Reader Tag to limit its duty cycle to intervals of
minutes or hours. After a prolonged period of inactivity, a
Wireless Reader Tag may ping (transmit) to determine whether other
Wireless Reader Tags are still alive and available for
communication. Assuming that no network changes have occurred, the
Wireless Reader Tag goes back to sleep until the next duty cycle.
Network changes may cause all or a part of a Class Based Network to
reconfigure.
[0107] With reference to FIG. 4, in response to the "primary_ready"
signal, Wireless Reader Tags of WRT Class "/circle" within range of
Wireless Reader Tag 1 respond with a registration request signal,
as listed in Table 1 of FIG. 23.
[0108] Because the registration request packets include in their
preambles a target WRT Class of Wireless Reader Tag 1, only
Wireless Reader Tag 1 will wake up from standby to receive and
process the registration request packets. The transmitters of
Wireless Reader Tags 2-6 would preferably 5 include conventional
collision avoidance routines to avoid interfering transmissions of
the registration request packets, as set forth by the Bluetooth
specifications.
[0109] With reference to FIG. 5, in response to receipt at Wireless
Reader Tag 1 of the registration request signals from Wireless
Reader Tags 2-6, the CBNF routine of Wireless Reader Tag 1
registers and acknowledges the secondary Wireless Reader Tags to
form a cluster. In this example, Wireless Reader Tag 1 has a
maximum cluster capacity of three secondary units. Consequently, it
only registers and acknowledges the three Wireless Reader Tags from
which the strongest registration request signals are received
which, in this example, are Wireless Reader Tags 2-4. (Note that
the ability of a LPRF device to determine signal strength is
conventional and, therefore, is not described in detail herein.) By
registering and acknowledging secondary units on the basis of
signal strength, rather than on a first-come-first-served basis or
some other basis, the CBNF routine establishes a cluster that is
energy efficient for communication within the cluster. To
acknowledge registration of the secondary units, Wireless Reader
Tag 1 transmits an acknowledgement signal to the Wireless Reader
Tags 2-4, as set forth in Table 2 of FIG. 24.
[0110] The network topology is now shown in FIGS. 6 and the cluster
hierarchy is depicted in FIG. 6A. The two concentric circles of
Wireless Reader Tag 1 indicate that it is a cluster head at Level 2
in the network hierarchy.
[0111] With reference to FIG. 7, with its cluster capacity now
exceeded, Wireless Reader Tag 1 (the cluster head) selects from the
other Wireless Reader Tags attempting to register the unit having
the strongest registration request signal (in this example Wireless
Reader Tag 5) and directs such unit to become a new primary unit.
The new primary unit then serves as a new cluster head for a
cluster in which Wireless Reader Tag 1 becomes a secondary unit
(thus the "bottom-up" description of the method). In this example,
the command from Wireless Reader Tag 1 to Wireless Reader Tag 5
is:
[0112] :/circle/unit5
:/circle/unit1:/promote_and_request_primary:no_primary
[0113] With reference to FIG. 8, Wireless Reader Tag 5 acknowledges
the promotion signal from Wireless Reader Tag 1 and begins to
propagate the Class Based Network at the next higher level in the
hierarchy, which now has three levels as depicted in FIG. 8A. In
acknowledging its promotion and registration as a primary to
Wireless Reader Tag 1, Wireless Reader Tag 5 transmits its
acknowledgement packet to all units of its class within range, by
the following preamble:
[0114]
:/circle:/circle/unit5:primary_acknowledged:/circle/unit5
[0115] By transmitting to all units of its WRT Class within range,
Wireless Reader Tag 5 efficiently registers with Wireless Reader
Tag 1 and concurrently shares primary status information with all
Wireless Reader Tags of its WRT Class within its broadcast range
(which is different from the go broadcast range of Wireless Reader
Tag 1). The three concentric circles around Wireless Reader Tag 5
indicate that it is a primary in the third-level of the hierarchy
of the Class Based Network.
[0116] With reference to FIGS. 9 and 9A, Wireless Reader Tag 6,
upon receiving Wireless Reader Tag 5's registration acknowledgement
(FIG. 8), requests to register as a secondary unit to Wireless
Reader Tag 5 by sending a packet with the following preamble:
[0117]
:/circle/unit5:/circle/unit6:request_primary:/circle/unit5
[0118] To which, unit 5 responds with:
[0119]
:/circle/unit6:/circle/unit5:registration_ackn:/circle/unit5
[0120] This exchange results in the hierarchy shown in FIG. 9A.
[0121] With reference to FIG. 10, a Class Based Network for the WRT
Class "/triangle" is similarly formed by Wireless Reader Tags A-G
concurrently with the steps shown in FIGS. 3-9, whereby two
distinct hierarchal Class Based Networks result as shown in FIG.
10A.
[0122] With reference to FIG. 11, if a Gateway is available, the
highest level primary units (Wireless Reader Tags 5 and A in this
example) register with the Gateway to establish connectivity to an
external network including an application server (not shown)
communicating therewith.
[0123] FIGS. 12-21 illustrate another preferred top-down CBNF
routine in which the Wireless Reader Tags transmit a series of
network formation communications in the course of self-organizing a
hierarchical network, the topology of which is shown at various
stages adjacent to FIGS. 13, 16, 19, and 21 in respective FIGS.
13A, 16A, 19A, and 21A. As with FIGS. 3-11, the transmitting
Wireless Reader Tags are shown in heavy bold outline, but the
hierarchical levels are not indicated this time by inner circles
and triangles.
[0124] With reference to FIG. 12, a first Wireless Reader Tag 1
wakes up and reads profile information stored in its memory,
including a predefined class designation of "/circle" as its WRT
Class. This profile is stored into the memory of the Wireless
Reader Tag 1 during an initialization of the Wireless Reader Tag 1.
Based on this class designation, Wireless Reader Tag 1 then listens
for transmission activity by other Wireless Reader Tags of the same
WRT Class. If the nearby Wireless Reader Tags of the WRT Class have
already formed a Class Based Network for "/circle" accordance with
the present invention, then Wireless Reader Tag 1 attempts to join
such Class Based Network. Otherwise, Wireless Reader Tag 1 attempts
to organize a Class Based Network for such WRT Class.
[0125] To begin organizing Class Based Network, Wireless Reader Tag
1 transmits a primary_ready signal including its designated WRT
Class. As in the CBNF routine described above in FIGS. 3-11 A, the
primary.sub..times.ready signal is preferably a data packet that
includes in its preamble data representative of the "circle" class
designation. In FIG. 12, the bold boundary of Wireless Reader Tag 1
indicates that it transmits rather than receives. The range of the
transmission is depicted by dashed circle R. Nearby Wireless Reader
Tags 2-5 and B, C, D, and E, which are within range of the
primary_ready signal, each processes only the preamble portion of
the primary_ready signal to determine whether the transmission if
from a Wireless Reader Tag of the same WRT Class. By first
processing only the preamble portion of the primary_ready signal,
battery power is conserved in triangle Wireless Reader Tags B, C,
D, and E. If it is of the same class, then the receiving Wireless
Reader Tag-in this example, each of Wireless Reader Tags 2-5 wakes
up, receives, and processes the entire primary_ready signal, and
then responds as shown in FIG. 13 and described below.
[0126] With reference to FIG. 13, each of the Wireless Reader Tags
of the WRT Class "/circle" that received the primary_ready signal
in FIG. 12 (i.e., units 2-5) responds to the primary_ready signal
with a registration request signal. Upon receipt of the
registration request signal, Wireless Reader Tag 1 assumes the
status of a primary unit, while Wireless Reader Tags 2-5 assume the
status of secondary units. FIG. 13A shows the resulting 2-tiered
network hierarchy tree representative of the Class Based Network
thus formed between Wireless Reader Tags 1-5.
[0127] Next, with reference to FIG. 14, a third tier of the
hierarchical network is formed by Wireless Reader Tag 6. In this
regard, Wireless Reader Tag 6 was out of range of Wireless Reader
Tag is primary_ready signal shown in FIG. 12, but is within range
of the registration request of Wireless Reader Tags 3 and 5 shown
in FIG. 13. Wireless Reader Tag 6, which was listening during the
step shown in FIG. 13, received the registration request signals of
Wireless Reader Tags 3 and 5 because those signals included the
"/circle" class designation matching the "/circle" class
designation of Wireless Reader Tag 6. The registration request
signals indicate to Wireless Reader Tag 6 the presence of a nearby
Class Based Network of corresponding WRT Class, which causes
Wireless Reader Tag 6 to transmit a request to join this Class
Based Network.
[0128] Concurrently with the ongoing formation of the "/circle"
class network, FIG. 14 also depicts the beginning stages of the
formation of a Class Based Network for the WRT Class of "/triangle"
by Wireless Reader Tags A-G. In this regard, Triangle Wireless
Reader Tag Awakes up and listens for the presence of a "/triangle"
class network. Detecting no other "/triangle" WRT Class signals,
Wireless Reader Tag A transmits a primary_ready signal, similar to
the transmission of Wireless Reader Tag 1 shown in FIG. 1, but with
a "/triangle" class designation forming part of the preamble of the
primary_ready signal.
[0129] With reference to FIG. 15, triangle class Wireless Reader
Tags B, C, and D receive the primary_ready signal of Wireless
Reader Tag A and respond with registration request signals, thereby
forming a second hierarchal Class Based Network, as shown in FIG.
16A.
[0130] Also shown in FIG. 15, circle Wireless Reader Tags 3 and 5
respond to the request to join of Wireless Reader Tag 6 of FIG. 14
with primary_ready signals. Wireless Reader Tag 6 then responds to
the strongest primary_ready signal received (in this example, the
signal from Wireless Reader Tag 5), with a registration request.
Wireless Reader Tag 6 thereby forms a third tier of the Class Based
Network for "/circle" WRT Class, also as shown in FIG. 16A.
[0131] With reference to FIGS. 1749, Wireless Reader Tags E, 45 F,
and G of the WRT Class "/triangle" each joins the Class Based
Network for triangles formed by Wireless Reader Tags A, B, C, and
D.
[0132] FIGS. 20-21A illustrate the completion of the Class Based
Networks with the registration with the Gateway of the highest
primary unit in each Class Based Network hierarchy.
[0133] As will now be apparent to one having ordinary skill in the
art, in conjunction with the asset-tracking application server,
Class Based Networks facilitate automated and semi-automated
segregation, tracking, monitoring, and delivery of assets. The
server issues, via the Gateway, class-directed messages to monitor
and track WRT Classes. User-defined class granularity facilitates
the use of separate categories and/or subcategories for various
attributes and states of the assets, e.g., production batches,
phases of production, and the delivery process. By increasing
granularity, i.e., using many categories or subcategories
(including sub-subcategories and so on), messages or other
class-directed communications from the application server can be
directed to only those classes of interest representing such
categories, subcategories, or sub-subcategories, as desired.
Furthermore, because messages or other class-directed
communications are transmitted in packets that specify class
designations for intended transceiver recipients, only those
transceivers that are members of the specified class awaken from
standby mode to receive and process the packets, and then to
acknowledge or reply thereto as appropriate. Accordingly, this
reduces RF interference and power consumption otherwise
experienced, while making assettracking functions more
efficient.
[0134] Once established, the Class Based Networks provide
functionality as a dynamic distributed hierarchical database
system. In this regard, Wireless Reader Tags and Wireless Tags
preferably include a handling routine in communication with a
memory of the Wireless Reader Tags and Wireless Tags. The handling
routine interprets and responds to class-directed database
commands, e.g., data queries or data updates from an asset-tracking
application or a Communicator. Database queries may include status
queries that provide the asset-tracking application with real-time
up-to-date status information about tagged assets. Data updates may
include requests to change data maintained on specified Wireless
Reader Tags of the distributed database system. Similar to network
formation communications, class-directed database commands include
preambles that identify a WRT Class of Wireless Reader Tags to
which they are directed. In this manner, only those Wireless Reader
Tags of the selected class need process the database command.
Class-directed database commands may also include, in their
preambles, a wildcard that indicates to query handling routines
that all Wireless Reader Tags of a particular abstracted WRT Class
should receive and process the database commands. Class-directed
commands thereby avoid unnecessary radio interference and reduce
power consumption by Wireless Reader Tags that are clearly outside
the scope of the database search criteria. Database performance is
also enhanced by selecting Wireless Reader Tag classes and class
abstractions in a way that mirrors a preferred hierarchical
structure for the data they contain. In this way, increased class
granularity facilitates improved data retrieval efficiency in the
distributed database system by reducing the number of Wireless
Reader Tags that must be involved in a database query or update
transaction. The Class Based Networks themselves act as a
hierarchical database facilitating fast and efficient database
queries.
[0135] The CBNF routine used to form the Class Based Networks in
accordance with the present invention may also be used to perform
autonomous modification and reconfiguration of such networks in
response to changes in the location, status, behavior,
characteristics or class designation of Wireless Reader Tags and/or
Wireless Tags. Similarly, the self-configuration methods of the
present invention facilitate maintenance of radio communication
links in response to changes in the operational characteristics of
the Wireless Reader Tags and/or Wireless Tags that comprise the
network fabric. For example, self-configuration routines are
responsive to changes caused by battery drain, radio transmitter
failures, radio interference, and digital processor failure, by
their inherent methods of organizing the network to have optimal
link integrity and node connectivity.
[0136] Functions/Commands
[0137] The following functions preferably are supported in a
Wireless Reader Tag of the present invention-and in a Wireless Tag,
where indicated-to accomplish the aforementioned class based
network formation and subsequent reformation. The name of the
function is followed by the description of the function in the
context of the type of transceiver in which it is to be
implemented, i.e., Wireless Reader Tag and/or Wireless Tag.
[0138] "Acquire Class or Sub-Class Structures"--Software on the
Wireless Reader Tags and Wireless Tags interprets category and
subcategory structures represented by WRT and WT Classes,
respectively. To initialize, the Wireless Reader Tags arbitrarily
form networks based on the ability to talk to other Wireless Reader
Tags. When a Wireless Reader Tags wakes up it broadcasts a message
to other Wireless Reader Tags that it is a primary unit seeking
secondary units. Other Wireless Reader Tags awaken to receive the
message and attempt to register with the primary unit. If they are
unable to communicate with the primary unit, or if the primary
unit's cluster is full, then the secondary units will attempt to
become a primary unit and continue the process. Once Wireless
Reader Tags have established a network, the highest primary unit of
the hierarchy contacts the Gateway and communicates with the
application server, whereupon a profile is downloaded to the
primary unit and passed on to each Wireless Tag of the network. The
profile downloaded is based on options such as reading Wireless
Tags, WRT IDs, business rules located at the application server and
other information that has been downloaded by a Communicator. For
example, and with regard to a WRT, the profile is a list of
attributes or "personalities" assigned to each WRT. The list in the
profile will be determined by business rules (like "things move
into the shipping are ready to be shipped", "all fresh meat
shipments must leave the plant within 24 hours of packing", etc.);
a Communicator (used, for example, by a supervisor who views the
asset and determines that it needs another coat of painting and
manually changes the class back to "pre-paint step", etc.); and
server application (first two-hundred assets shipped to New Jersey,
next two-hundred assts shipped to Florida, last five-hundred assets
shipped to California, etc.). The profile function can allow
conditional class change.
[0139] Once the Wireless Reader Tags have their respective
profiles, the Wireless Reader Tags reform in Class Based Networks
based on rules defined by the software located on the Wireless
Reader Tags. If read-only Wireless Tags are used, then the WR Class
can be preprogrammed into the Wireless Tags but will not be able to
be modified dynamically. The dynamic acquisition of a WRT Class is
based on rules defined by the application server.
[0140] "Allow Class/State Change"--Class changes are allowed based
on business rules setup by the customer to track and group their
assets. The rules are built into the server application and the
software on the Wireless Reader Tags. The profile provides
information that allows dynamic decisions to be made by the
Wireless Reader Tags. Once the Wireless Reader Tags have determined
that their category, subcategory, etc. as represented by their WRT
Class has changed, the Wireless Reader Tags must join the new WRT
Class. The ability to allow such a class change provides
functionality to allow dynamic changes to WRT Class by a Wireless
Reader Tag. For example, with reference to FIGS. 10 and 10A,
changing the WRT Class of the Wireless Reader Tag E to "/circle"
from "/triangle" causes Wireless Reader Tag E it to join the Class
Based Network for the circle, either as a secondary unit in a
cluster of an existing primary unit (e.g., circle Wireless Reader
Tag 5), or by becoming a primary unit itself. Continued contact
between Wireless Reader Tag E and the WRT Class of triangles could
be limited based on system rules, but preferably is terminated. In
an example of this, the WRT class of triangles could represent
goods in the process of being manufactured in a factory. When these
goods enter a shipping section of the factory, the Wireless Reader
Tags associated with the goods on the pallet would automatically
acquire a "shipping" WRT Class representative of their current
location and associated status in shipping.
[0141] "Form Class"--A Class Based Network for a new class can be
established by downloading a new profile and using the command
"Determine Primary". The command then uses techniques in FIGS. 2-21
to establish the Class Based Network for the new class. Profiles
and software on the Wireless Reader Tags form the basis for
decisions on network formation. The profile must be preprogrammed
in the Wireless Reader Tags or Wireless Tags or downloaded from the
application server.
[0142] "Combine Classes"--The combination of classes is required
when the user no longer wishes to differentiate between two
originally defined classes. The profile is downloaded either as a
new class profile that a new class name or downloads to the class
to be replaced by the existing class. After combining classes, the
Wireless Reader Tags may reform the network using the CBNF routines
of the present invention.
[0143] "Determine Primary"--When a Wireless Reader Tag "wakes up",
it determines whether it is able to become a primary unit with the
determine primary command. If the health of the device is
sufficient, it sends out a message to other Wireless Reader Tags of
its WRT Class for registration of secondary units.
[0144] "Ping MLG/Gateway/Communicator"--A Wireless Reader Tag
incorporated into a MLG, Gateway, or Communicator sends out a
special message identifying itself as part of an MLG, Gateway, or
Communicator. The purpose of this message is to inform other
Wireless Reader Tags in standalone mode that the Wireless Reader
Tag incorporated into the MLG, Gateway, or communicator has
additional capabilities. The identifying message allows the
Communicator to query information from the Wireless Reader Tags or
Wireless Tags while the message from the Gateway and MLG indicate
an ability to communicate to the external network.
[0145] "Inventory WT Tags"--The Wireless Reader Tag will read all
Wireless Tags within range. The profile downloaded from the
application server will help the Wireless Reader Tag control
misreads and extra tags. Multiple reads of the tags insures high
reliability.
[0146] "Report Communication Links"--Upon formation of a Class
Based Network, a Wireless Reader Tag stores identifiers that
describe the Wireless Reader Tags constituting neighbors in
adjacent levels of the network hierarchy. The primary unit thus
will store all the WRT IDs for its secondary units, while the
secondary units will store the WRT IDs on the primary unit and any
secondary units thereto. The knowledge of communication links, both
upstream and downstream, supports responsiveness to queries from
the application server.
[0147] "Report Local Classes"--By listening for preambles of data
packets intended for other classes, Wireless Reader Tag may store
WRT Class information about other Wireless Reader Tags in their
vicinity. The Wireless Reader Tags will support queries from the
application server to supply this intelligence regarding local
class information, regardless of whether the reported class even
maintains connectivity to the application server.
[0148] "Class Structure-Secondary only"--The secondary only command
provides entry into a system without giving network formation
rights. In this regard, the Wireless Reader Tag with this
designation in the profile is allowed to act like the other
secondary Wireless Reader Tags, but it is unable to take on the
role of a primary unit and, thus, is itself restricted from further
propagating the network. This allows the Wireless Reader Tag the
ability to move from one WRT Class to another WRT Class without
otherwise disturbing the hierarchy of each Class Based Network of
which it becomes a part. A practical of this command enables a
customer, who walks into a warehouse retailer, to read product
names, costs, or locations in the store without interrupting or
disturbing the resident asset-tracking application.
[0149] Server Assisted Network Formation
[0150] The CBNF routines described above with reference to FIGS.
3-11 and 12-21 involved peer-centric network formation, in which
Wireless Reader Tags self-formed an ad hoc Class Based Network and
then contacted an application server via a Gateway. In this
peer-centric method, each Wireless Reader Tag contains software
that is preprogrammed to interpret class information contained in
the of messages being transmitted by other Wireless Reader Tags and
then negotiate to be a primary unit. The Wireless Reader Tags use
commands such as inventory Wireless Tags, determine primary, and
others (described above) to make decisions on class and other
profile information that has been preprogrammed in the Wireless
Reader Tags. Once the Wireless Reader Tags have formed the Class
Based Network, information is transmitted by the Wireless Reader
Tags for connectivity to server applications.
[0151] Other network propagation methods within the scope of the
present invention are contemplated, and include a server-initiated
method and a client/server shared method. In the server-initiated
method, the Wireless Reader Tags are attached to pallets or areas
to read information from Wireless Tags. The Wireless Reader Tags
are turned on and first form an arbitrary network using commands
such as Determine Primary. This arbitrary formation is done so that
the server can address particular Wireless Reader Tags, and the
formation is not based on class designations. The Wireless Tags are
read by the Wireless Reader Tags and profiles are downloaded to the
Wireless Tags from the Wireless Reader Tags based on commands such
as "Inventory RF Tags", described above. Profiles defining a new
class structure are then downloaded from the server to the Wireless
Reader Tags (and any read/write Wireless Tags) based on business
rules. The Wireless Reader Tags are then instructed to Determine
Primary again, whereby Class Based Networks are formed according to
the newly-assigned class structure. In this regard, the profiles
are lists of options that the Wireless Reader Tag can use to make
decisions. For example, if a pallet has TVs on it and the profile
lists possible products as VCRs, TVs, Cameras and Unknown, then the
Wireless Reader Tag knows to adopt the class of TVs and form a
network accordingly. If TV was not in the list, then the Wireless
Reader Tag could adopt the class 50 Unknown and generate a system
flag for further analysis.
[0152] In the client/server shared method, the Wireless Reader Tags
are loaded with software preprogrammed to interpret profile
information. The profile information may include WT IDs, states,
and the like. The Wireless Reader Tags then are reset and boot up
looking to read the saved profile, to form hierarchical networks
based on class designations specified in the profile, and to look
for primary/secondary configurations. Once the Wireless Reader Tags
have setup the initial network, network server business rules are
downloaded to the Wireless Reader Tags in the form of new profiles
to "fine tune" the network. In this regard, general information
about how a particular business operates is used to setup the
network. Not enough information is known, however, about the
assets. In this case, information can be stored in the Wireless
Tags as they are attached to the assets, and profiles in the
Wireless Reader Tags can enable the Wireless Reader Tags to read
this information and make intelligent decisions about how to
efficiently setup the network so that the data is an organized
within the database in a performance-enhancing fashion.
[0153] The following are examples of asset-tracking applications
within the scope of the present invention.
EXAMPLE 1
[0154] Tagged Luggage System
[0155] When a passenger checks in at the airport a Wireless Tag is
attached to each item of the passenger's luggage. A corresponding
Wireless Tag identifying the passenger is provided to the passenger
to verify his/her identity at the destination baggage pickup
location. A Wireless Reader Tag near the check-in counter detects
and logs the Wireless Tags for the luggage in association with the
passenger's Wireless Tag and related information into the
asset-tracking system. The asset-tracking system downloads a
profile into each of the Wireless Tags as identified by the
Wireless Reader Tag at the check-in counter. The profiles are in
the format:
[0156]
:Tag.sub..times.Type:Airline_Name:Passenger_Class:Origin_and_Destin-
ation:Flight
[0157] An example of the profile for the passenger's Wireless Tag
is:
[0158]
passenger:Delta_Airlines:First_Class:ATL-SEA:FLT-490:check-in:
45567788KDKO8
[0159] while an example of the profile for the luggage Wireless Tag
is:
[0160] :baggage:Delta_Airlines:FirstClass:ATL-SEA:FLT-490:check-in:
45567788KDKO8
[0161] Upon successful check-in, the luggage is placed on the
conveyer belt where it is read by another Wireless Reader Tag. By
way of a communication from the Wireless Reader Tag, the profile of
each Wireless Tag on the luggage then is modified by altering the
Tag Status field from "check-in" to "luggage-transfer
station_4334," which identifies a location of the Wireless Reader
Tag at the conveyor belt. Multiple Wireless Reader Tags are
positioned along the conveyer belt system to identify the specific
area of location of the luggage as it progresses. Trucks that
deliver the luggage to the plane also have Wireless Reader Tags
attached to the truck and alter the Tag Status to "departure
on-transfer-truck-1441". Once the luggage is placed on the plane,
yet another Wireless Reader Tag detects and logs the Wireless Tag
into the asset-tracking system, whereupon a cross-check is made of
the luggage as identified by the WT IDs with the luggage that is
supposed to be on the plane. Any luggage that is not supposed to be
on the plane is flagged for removal by the asset-tracking system
and rerouted to its proper destination. Any luggage that is not
accounted for raises an alarm, so that attendants are alerted to
its arrival time, its position, or its last known position and an
investigation can be made.
[0162] Once the plane arrives at its destination, the Wireless Tags
of the luggage are detected and logged in by an Wireless Reader Tag
and the Tag_Status field of each Wireless Tag is changed to
"arrival_on-transfer-truck-6633". At the destination baggage
pickup, the Wireless Tags on the luggage are read by a Wireless
Reader Tag located near an exit of the baggage area. The Wireless
Reader Tag detects and logs the luggage Wireless Tags in
association with the Wireless Tag of the passenger claiming the
luggage, whereupon the asset-tracking system assures that the
passenger claiming the luggage is authorized to do so. A passenger
inadvertently selecting the wrong luggage may then be alerted to
the error.
EXAMPLE 2
[0163] Warehouse/Retail System
[0164] A warehouse store such as Costco carries hundreds of brands
of products. Nevertheless, all products need to be inventoried on a
real-time basis. In accordance with the present invention, a
Wireless Reader Tag is attached to each pallet of goods and
assigned a class designation that denotes the manufacturer of goods
on that pallet (e.g., Pillsbury, Sony, Kellogg's, etc.). Each
Wireless Reader Tag may also include in its class designation or
profile, information about the goods on the pallet. Each boxes on
the pallet carries a Wireless Tag that is read by the Wireless
Reader Tag of the pallet. On demand, each Wireless Reader Tag
gathers information about the Wireless Tags on its pallet and
relays the information back to the asset-tracking application
server. At any given time, an employee of the warehouse store can
inventory goods of a selected manufacturer by sending a query that
will be received only by Wireless Reader Tags of the selected class
corresponding to such manufacturer. Messages directed to a selected
class will not appreciably affect the battery life of Wireless
Reader Tags of other classes, as only Wireless Reader Tags of the
selected class will wake up from standby mode to receive the
messages and process the query. The manufacturer classes can be
divided further into categories and subcategories, thereby further
collectively reduce battery consumption and radio interference.
EXAMPLE 3
[0165] Shipping Containers Tracking System
[0166] Containers full of material shipped via rail or ship can be
received and logged into a yard by manufacture based on class
information stored on Wireless Reader Tags. The Wireless Reader
Tags form a network with other containers from a particular
manufacturer and allow quick and efficient tracking of containers.
Messages directed to a selected class will not affect the battery
life of Wireless Reader Tags of other classes because only Wireless
Reader Tags of the selected class will wake up from standby to
receive the messages and process the queries. The manufacturer
classes can be divided into categories and subcategories, thereby
further collectively reduce battery consumption and radio
interference.
EXAMPLE 4
[0167] Manufacturing and Supply Chain Tracking System
[0168] A computer manufacturer may track the status of its supply
chain in accordance with the asset-tracking application of the
present invention. The classes defined are "raw material,"
"component stuffing," "monitor assembly," "final assembly,"
"shipping," "in transit," and "distributor." The manufacture can
inventory raw material throughout the process by addressing the raw
material class, and can find out where in the manufacturing process
the computer has reached by addressing monitor assembly or final
assembly classes.
[0169] In view of the foregoing detailed description of preferred
embodiments of the present invention, it readily will be understood
by those persons skilled in the art that the present invention is
susceptible of broad utility and application. While various aspects
have been described in the context of arborist uses, the aspects
may be useful in other contexts as well. Many embodiments and
adaptations of the present invention other than those herein
described, as well as many variations, modifications, and
equivalent arrangements, will be apparent from or reasonably
suggested by the present invention and the foregoing description
thereof, without departing from the substance or scope of the
present invention. Furthermore, any sequence(s) and/or temporal
order of steps of various processes described and claimed herein
are those considered to be the best mode contemplated for carrying
out the present invention. It should also be understood that,
although steps of various processes may be shown and described as
being in a preferred sequence or temporal order, the steps of any
such processes are not limited to being carried out in any
particular sequence or order, absent a specific indication of such
to achieve a particular intended result. In most cases, the steps
of such processes may be carried out in various different sequences
and orders, while still falling within the scope of the present
inventions. Accordingly, while the present invention has been
described herein in detail in relation to preferred embodiments, it
is to be understood that this disclosure is only illustrative and
exemplary of the present invention and is made merely for purposes
of providing a full and enabling disclosure of the invention. The
foregoing disclosure is not intended nor is to be construed to
limit the present invention or otherwise to exclude any such other
embodiments, adaptations, variations, modifications and equivalent
arrangements, the present invention being limited only by the
claims appended hereto and the equivalents thereof.
[0170] For example, those skilled in the art now also will
recognize that methods of network formation other than the
described top-down and bottom-up processes may be used to propagate
a Class Based Network based on a multi-level hierarchy by the
Wireless Reader Tags. For example, a middle-outward approach or
star configuration may be used to propagate the hierarchical
network.
[0171] Also, for purposes of describing preferred embodiments of
the present invention, it has been assumed herein that each WRT
Class has more than one member. Otherwise, the sole member of the
WRT Class communicates directly with a Gateway. However, this
scenario is contemplated within the scope of the present
invention.
[0172] Furthermore, while each Wireless Reader Tag has been
described as belonging to a particular WRT Class, class membership
for each Wireless Reader Tag need not necessarily be exclusive, and
a Wireless Reader Tag therefore may belong to more than one WRT
Class as desired in any particular application of the present
invention. Moreover, while each WRT Class has been described as
reading a particular WT Class associated therewith, each Wireless
Reader Tag may read Wireless Tags associated with different WRT
Classes, as desired in the asset-tracking application.
[0173] With regard to the distinction between Wireless Reader Tags
and Wireless Tags, it is noted that each Wireless Reader Tag
includes the capabilities of each Wireless Tag and, therefore, it
is contemplated within the scope of the present invention that each
Wireless Tag of the present invention could be replaced with a
Wireless Reader Tag.
[0174] Finally, if a Wireless Tag is passive, which is contemplated
within the scope of the present invention, then it is believed that
the Wireless Tag currently maintains therein only its unique WT ID.
Being passive, no other information is maintained in the Wireless
Tag. In this case, an associated Wireless Reader Tag maintains the
identification of its WT Class in memory as indexed by the
respective WT ID of the passive Wireless Tag. Any other
information, if maintained, also is stored in the Wireless Reader
Tag and indexed by WT ID, where appropriate. Of course, in this
scenario, any broadcast generally is answered by each passive
Wireless Tag that is within broadcast range and, hence, such
implementation of passive Wireless Tags, while within the scope of
the present invention, is not preferred.
* * * * *