U.S. patent application number 15/866782 was filed with the patent office on 2019-07-11 for rfid system with antenna integrated in a luminaire.
The applicant listed for this patent is ABL IP HOLDING LLC. Invention is credited to Youssef F. BAKER, Niels G. EEGHOLM, Nathaniel W. HIXON, Yenpao LU, Jack C. RAINS, JR., David P. RAMER, Sean P. WHITE.
Application Number | 20190213368 15/866782 |
Document ID | / |
Family ID | 67106429 |
Filed Date | 2019-07-11 |
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United States Patent
Application |
20190213368 |
Kind Code |
A1 |
WHITE; Sean P. ; et
al. |
July 11, 2019 |
RFID SYSTEM WITH ANTENNA INTEGRATED IN A LUMINAIRE
Abstract
A lighting system includes luminaires each having a light source
for providing illumination in a space and a radio frequency
identification (RFID) antenna. An RFID reader is coupled to the
RFID antennas in all the luminaires. The RFID reader may transmit
at least one RFID intended recipient message from at least one of
the antennas and receive a responsive RFID reply message from a
recipient device within the space via a plurality of the antennas.
The RFID reader may determine a signal attribute of a reply message
signal received via each receiving antenna. The determined signal
attributes of the reply message signals received via antennas and
information about locations of the receiving antennas are processed
to estimate a position of the recipient device within the
space.
Inventors: |
WHITE; Sean P.; (Reston,
VA) ; HIXON; Nathaniel W.; (Arlington, VA) ;
EEGHOLM; Niels G.; (Columbia, MD) ; BAKER; Youssef
F.; (Arlington, VA) ; LU; Yenpao; (Cumming,
GA) ; RAINS, JR.; Jack C.; (Herndon, VA) ;
RAMER; David P.; (Reston, VA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ABL IP HOLDING LLC |
Conyers |
GA |
US |
|
|
Family ID: |
67106429 |
Appl. No.: |
15/866782 |
Filed: |
January 10, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G06K 7/10445 20130101;
G07C 9/28 20200101; G06K 7/10099 20130101; H05B 47/19 20200101 |
International
Class: |
G06K 7/10 20060101
G06K007/10; G07C 9/00 20060101 G07C009/00; H05B 37/02 20060101
H05B037/02 |
Claims
1. A lighting system, comprising: a plurality of luminaires located
within a space, wherein each luminaire of the plurality of
luminaires includes: a light source configured to provide general
illumination light to the space, and an antenna configured for
wireless radio frequency communication within the space; and a
radio frequency identification reader, the radio frequency
identification reader comprising: a reader processor to control
operation of the radio frequency identification reader; a reader
radio frequency transceiver coupled to the reader processor; a
selectable antenna interface coupled to the processor and the
reader transceiver, the antenna interface being configured to
selectively couple each antenna of the plurality of luminaires
within the space to the reader transceiver; and a data storage
device storing a unique identifier for each antenna; wherein the
reader processor is configured to perform functions, including
functions to, iteratively, for each respective one or more of the
antennas in each of the luminaires: control the selectable antenna
interface to selectively couple the respective one or more antennas
to the reader transceiver; control the reader transceiver to
transmit an intended recipient message from a selected antenna of
the respective one or more antennas for reception by an intended
recipient device, wherein the transmitted intended recipient
message contains the unique identifier of the selected antenna and
an address of the intended recipient device within the space; in
response to the transmitting of the intended recipient message,
receive via at least one of the respective one or more antennas a
reply message from the intended recipient device; obtain a signal
attribute of the received reply message; and maintain a record in
the data storage device for each iteration, the record including
the obtained signal attribute in association with the unique
identifier of the selected antenna and the intended recipient
address.
2. The lighting system of claim 1, further comprising a server
coupled to the data storage, wherein the server comprises a
processor and memory, the memory storing programming instructions
which upon execution by the server processor configures the server
to perform functions, including functions to: retrieve a respective
first, second and third record from the data storage; determine,
using the obtained attribute in each of the respective first,
second and third records, a distance measure of the intended
recipient device from the selected antenna identified in each of
the first, second and third records; and using the distance
measures determined from each of the first, second and third
records and known locations of the selected antennas of identified
in the respective first, second and third records, calculate a
position of the intended recipient device with respect to the
selected antennas of identified in the respective first, second and
third records.
3. The lighting system of claim 1, further comprising: a responsive
radio frequency device having an address matching the address
contained in the intended recipient message, wherein the responsive
radio frequency device comprises an antenna, modulation circuitry,
and logic circuitry, and is configured to: receive the intended
recipient message via the antenna of the responsive radio frequency
device; determine, via the logic circuitry, that the received
intended recipient message is addressed to the responsive radio
frequency device by comparing the address in the intended recipient
message to an address of the responsive radio frequency device; and
in response to the determination that the responsive radio
frequency device is the intended recipient device, generate, by the
modulation circuitry, the reply message including the intended
recipient device address that is the address of the responsive
radio frequency device.
4. The lighting system of claim 1, wherein the reply message
further includes the unique identifier of the selected antenna.
5. The lighting system of claim 1, wherein when obtaining the
signal attribute of the received reply message, the reader
processor is further configured to perform functions, including
functions to: retrieve a received signal strength indication value
corresponding to a measured received signal strength of the
received reply message.
6. The lighting system of claim 1, wherein when obtaining the
signal attribute the received reply message, the reader processor
is further configured to perform functions, including functions to:
retrieve a time stamp corresponding to a time when the received
reply message was received by the respective selected antenna.
7. The lighting system of claim 1, wherein when obtaining the
signal attribute the received reply message, the reader processor
is further configured to perform functions, including functions to:
retrieve a signal phase representation corresponding to a signal
phase of the received reply message when received by the respective
selected antenna.
8. A system, comprising: a plurality of luminaires located within a
space, wherein each luminaire of the plurality of luminaires
includes: a light source configured to provide general illumination
light to the space, and an antenna configured for wireless radio
frequency communication within the space; and a radio frequency
identification reader, the radio frequency identification reader
comprising: a reader processor configured to control operation of
the radio frequency identification reader; and a reader radio
frequency transceiver coupled to the reader processor, the reader
transceiver configured to emit a signal to an antenna selected from
the plurality of antennas, and receive reply messages in response
to the emitted signal; a selectable antenna interface coupled to
the processor, the reader transceiver, and to each respective
antenna of the plurality of luminaires within the space, the
selectable antenna interface configured to: in response to an
antenna selection signal received from the reader processor,
communicatively couple at least one selected antenna of the
plurality of antennas to the reader transceiver, wherein each
antenna has a unique identifier; and a data storage device storing
the unique identifier for each respective antenna of the plurality
of antennas, wherein the reader processor is further configured to
determine an attribute of the received reply message usable in
estimating a location within the space from which the received
reply message was transmitted.
9. The system of claim 8, wherein the attribute of the received
reply message is at least one of received signal strength, phase,
or time difference of arrival.
10. The system of claim 8, wherein the radio frequency
identification reader is collocated with one luminaire of the
plurality of luminaires.
11. The system of claim 8, wherein the radio frequency
identification reader is located remotely from the plurality of
luminaires.
12. The system of claim 8, wherein: the plurality of luminaires are
a subset of a larger group of luminaires, and each radio frequency
identification reader being coupled to a server, wherein the server
is configured to: retrieve the determined attributes for the
received reply messages, and estimating the location within the
space from which the received reply message was transmitted.
13. The system of claim 8, wherein each antenna of each respective
luminaire of the plurality of luminaires is integrated into a
diffuser of each respective luminaire.
14. A radio frequency identifier reader, comprising: a reader
processor configured to control operation of the radio frequency
identification reader; a selectable antenna interface coupled to
the processor and to each respective antenna of a plurality of
antennas located within the space, a data storage device coupled to
the reader processor, the data storage device configured to store a
unique identifier for each respective antenna of the plurality of
antennas and other data, a reader radio frequency transceiver
coupled to the reader processor and the selectable antenna
interface, wherein the reader transceiver is configured to: emit a
signal from an antenna selected from the plurality of antennas, and
receive reply messages in response to the emitted signal; and
wherein the selectable antenna interface is configured to: in
response to an antenna selection signal received from the reader
processor, communicatively couple at least one selected antenna of
the plurality of antennas to the reader transceiver.
15. (canceled)
16. A method, comprising: during an iteration of an iterative
process: selecting an available antenna from a plurality of
antennas as a currently active antenna, wherein each of the
plurality of antennas is: coupled to a respective luminaire of a
plurality of luminaires located within a space, assigned a unique
identifier, and upon selection of the currently active antenna in
the current iteration, generating a message containing an address
of an intended recipient and a unique identifier of the antenna
selected as the currently active antenna; transmitting, via a radio
frequency (RF) transceiver coupled to the currently active antenna,
the generated message into the space; in response to the
transmitted message, receiving via the currently active antenna a
reply message from the intended recipient device; determining a
reply message attribute of the received reply message; and storing
in memory the determined reply message attribute and the unique
identifier of the currently active antenna in association with the
intended recipient address, wherein upon completion of the
iterative process the memory contains records of a plurality of
determined reply message attributes corresponding to each
respective antenna; determining a location within the space from
which the received reply message was transmitted based on the
determined reply message attribute; and selecting another antenna
from the plurality of antennas to replace the currently active
antenna in a next iteration of the iterative process.
17. The method of claim 16, further comprising: after completion of
the iterative process, retrieving from the memory the records of a
plurality of determined reply message attributes corresponding to
the intended recipient address.
18. The method of claim 16, wherein: the determined reply message
attributes are a received signal strength indication value
corresponding to a measured received signal strength of the
received reply message from the intended recipient address at a
respective antenna identified in the records, and the step of
determining a location with the space comprises: determining
respective distances from each respective antenna to the location
of the space using the respective received signal strength
indication values, and applying trilateration techniques to the
determined respective distances to determine the location within
the space from which the reply message was transmitted.
19. The method of claim 16, wherein: the determined reply message
attributes are time stamps corresponding to a time when the
received reply message was received at a respective antenna
identified in the records, and the step of determining a location
with the space comprises: determining respective distances from
each respective antenna to the location of the space using the
respective time stamps, and applying trilateration techniques to
the determined respective distances to determine the location
within the space from which the reply message was transmitted.
20. The method of claim 16, wherein: the determined reply message
attributes are signal phase representations corresponding to a
signal phase of the received reply message at a respective antenna
identified in the records, and the step of determining a location
with the space comprises: determining respective distances from
each respective antenna to the location of the space using the
respective signal phase representations, and applying trilateration
techniques to the determined respective distances to determine the
location within the space from which the reply message was
transmitted.
21. A lighting system, comprising: one or more luminaires, each
luminaire comprising a light source configured to provide general
illumination in a space; radio frequency identification (RFID)
antennas incorporated in the one or more luminaires; an RFID reader
transceiver coupled to the RFID antennas; and an RFID reader
processor coupled to the RFID transceiver, wherein: the RFID reader
processor is configured to cause the RFID reader transceiver to
transmit at least one RFID intended recipient message from at least
one of the antennas and to receive a responsive RFID reply message
from a recipient device within the space via a plurality of the
antennas; and the RFID reader processor is further configured to:
determine a signal attribute of a reply message signal received via
each antenna of the plurality of antennas; and process the
determined signal attributes of the reply message signals received
via the plurality of antennas and information about locations of
the plurality of antennas to estimate a position of the recipient
device within the space.
22. The lighting system of claim 21, wherein: at least two of the
RFID antennas are collocated in one luminaire of the one or more
luminaires.
23. The lighting system of claim 21, further comprising: more than
one luminaire, wherein each luminaire has at least one antenna of
the RFID antennas collocated with the luminaire.
24. A method, comprising: transmitting, by a radio frequency
identification (RFID) transceiver coupled to a plurality of RFID
antennas in one or more luminaires in a lighting system, an RFID
intended recipient message from at least one of the antennas,
receiving a responsive RFID reply message signal from a recipient
device within the space via a plurality of the antennas;
determining by the RFID processor a signal attribute of the reply
message signal received via each antenna of the plurality of the
antennas; and processing the determined signal attributes of the
reply message signals received via the plurality of antennas and
information about locations of the plurality of antennas to
estimate a position of the recipient device within the space.
Description
TECHNICAL FIELD
[0001] The subject matter of this application is directed a radio
frequency identification detection (RFID) reader coupled to one or
more antennas integrated into each respective one or a number of
luminaires.
BACKGROUND
[0002] As is well known, RFID readers communicate with either
passive or active "tags" that respond to signals emitted by
respective RFID readers. Systems including the tags and RFID
readers have been used for many years to track inventory and items,
even persons, in different types of spaces, such as factories,
warehouses, retail establishments, hospitals, marathon races, and
the like.
[0003] As mentioned, the tags may be either passive or active.
Passive tags are tags that do not carry a separate power supply,
but instead derive their power from the energy of the signals
received from RFID readers. Conversely, active tags are tags
equipped with separate power supplies, such as batteries, solar
cells or the like. An RFID reader may emit a signal that triggers
an RFID tag to send back a response signal carrying the
identification (ID) associated with the tag. The RFID reader
receives the response signal from the tag and captures the tag ID,
for further use according to the particular application of the RFID
system.
[0004] Regardless of whether the tags are passive tags or active
tags, RFID readers can be placed in various locations such as
walls, light switches, counter tops, door way scanning devices,
ceilings, and the like. One device that is ubiquitous in spaces
such as the factor, warehouse, retail establishment and hospital
are light fixtures.
[0005] It has been suggested to incorporate an RFID reader and the
antenna required to receive responses from tags in the space in a
light fixture, or even into a light bulb. However, these systems
require each RFID-enabled light fixture to have both a suitable
antenna and an associated RFID reader, which result in systems that
are expensive to implement and include redundant devices.
SUMMARY
[0006] Hence, there is a need for improvement in the utilization of
RFID systems to more accurately and efficiently, through cost
reduction and implementation measures, locate equipment for reading
RFIDs to perform RFID reader functions in a space.
[0007] By way of an example, a lighting system includes luminaires
located within a space and a radio frequency identification reader.
Each of the luminaires includes a light source and an antenna. The
light source may be configured to provide general illumination
light to the space. The antenna may be configured for wireless
radio frequency communication within the space. The radio frequency
identification reader includes a reader processor, a reader radio
frequency transceiver, a selectable antenna interface and a data
storage. The reader processor controls operation of the radio
frequency identification reader. The reader processor is coupled to
the reader radio frequency transceiver, the selectable antenna
interface and the data storage. The selectable antenna interface is
selectively coupled to each antenna of the luminaires within the
space. The data storage device stores a unique identifier for each
antenna. The reader processor is configured to iteratively perform
functions for each respective one or more of the antennas in each
of the luminaires, including controlling the selectable antenna
interface to selectively couple the respective one or more antennas
to the reader transceiver. The reader transceiver is controlled by
the processor to transmit an intended recipient message from a
selected antenna of the respective one or more antennas for
reception by an intended recipient device. The transmitted intended
recipient message contains the unique identifier of the selected
antenna and an address of the intended recipient device within the
space. The processor is configured to, in response to the
transmitting of the intended recipient message, receive via at
least one of the respective one or more antennas a reply message
from the intended recipient device. A signal attribute of the
received reply message is obtained. A record is maintained in the
data storage device for each iteration. The record includes the
obtained signal attribute in association with the unique identifier
of the selected antenna and the intended recipient address.
[0008] By way of another system example, the disclosure provides
luminaires located to provide illumination lighting within a space
and a radio frequency identification reader. Each luminaire
includes a light source and an antenna. The light source is
configured to provide general illumination light to the space. The
antenna is configured for wireless radio frequency communication
within the space. The radio frequency identification reader
includes a reader processor, a reader radio frequency transceiver,
a selectable antenna interface, and a data storage. The reader
processor is configured to control operation of the radio frequency
identification reader. The reader radio frequency transceiver is
coupled to the reader processor. The reader transceiver is
configured to emit a signal to an antenna selected from the
plurality of antennas, and receive reply messages in response to
the emitted signal. The selectable antenna interface is coupled to
the processor, the reader transceiver, and to each respective
antenna of the plurality of luminaires within the space. The
selectable antenna interface is configured to be communicatively
coupled at least one selected antenna of the antennas to the reader
transceiver in response to an antenna selection signal received
from the reader processor. Each of the plurality of antennas has a
unique identifier. The data storage device stores the unique
identifier for each respective antenna. The reader processor is
further configured to determine an attribute of the received reply
message usable in estimating a location within the space from which
the received reply message was transmitted.
[0009] Also, disclosed in an example is a radio frequency
identifier reader. The radio frequency identifier reader includes a
reader processor, a reader radio frequency transceiver, and a
selectable antenna interface. The reader processor is configured to
control operation of the radio frequency identification reader. The
selectable antenna interface is coupled to the processor and to
each respective antenna of the antennas located within the space.
The reader radio frequency transceiver is coupled to the reader
processor and the selectable antenna interface. The reader
transceiver is configured to emit a signal from an antenna selected
from the antennas, and receive reply messages in response to the
emitted signal. The selectable antenna interface configured to, in
response to an antenna selection signal received from the reader
processor, communicatively couple at least one selected antenna of
the antennas to the reader transceiver.
[0010] An example of a process is also provided in the disclosure.
The process is an iterative process. During an iteration of an
iterative process, an available antenna from a number of antennas
is selected as a currently active antenna. Each of the plurality of
antennas is coupled to a respective luminaire of a number of
luminaires located within a space and assigned a unique identifier.
The processor, upon selection of the currently active antenna in
the current iteration, generates a message containing an address of
an intended recipient and a unique identifier of the antenna
selected as the currently active antenna. The generated message is
transmitted, via a radio frequency (RF) transceiver coupled to the
currently active antenna, into the space. A reply message from the
intended recipient device is received via the currently active
antenna in response to the transmitted message. A reply message
attribute of the received reply message is determined. The
determined reply message attribute and the unique identifier of the
currently active antenna in association with the intended recipient
address is stored in memory. Upon completion of the iterative
process the memory contains records of a plurality of determined
reply message attributes corresponding to each respective antenna.
A location within the space is determined from which the received
reply message was transmitted based on the determined reply message
attribute. Another antenna from the number of antennas is selected
to replace the currently active antenna in a next iteration of the
iterative process.
[0011] Another example provides a lighting system. The lighting
system includes luminaries, an RFID reader transceiver and an RFID
reader processor. Each luminaire includes a light source configured
to provide general illumination in a space and a radio frequency
identification (RFID) antenna. The RFID reader transceiver is
coupled to the RFID antennas in all the luminaires. The RFID reader
processor is coupled to the RFID transceiver. The RFID reader
processor is configured to cause the RFID reader transceiver to
transmit at least one RFID intended recipient message from at least
one of the antennas and to receive a responsive RFID reply message
from a recipient device within the space via a plurality of the
antennas. The RFID reader processor is further configured to
determine a signal attribute of a reply message signal received via
each antenna of the number of antennas; and process the determined
signal attributes of the reply message signals received via the
number of antennas and information about locations of the number of
antennas to estimate a position of the recipient device within the
space.
[0012] In yet another method example, a method is disclosed that
provides a radio frequency identification (RFID) transceiver
coupled to RFID antennas in a plurality of luminaires in a lighting
system that transmits an RFID intended recipient message from at
least one antenna in a respective one of the plurality of
luminaires. A responsive RFID reply message signal is received from
a recipient device within the space via the plurality of the
antennas. The RFID processor determines a signal attribute of the
reply message signal received via each antenna of the plurality of
antennas. The determined signal attributes of the reply message
signals received via the plurality of antennas and information
about locations of the plurality of antennas are processed. The
position of the recipient device within the space is estimated
based on the processed signal attributed of the reply message
signals and information about locations of the plurality of
antennas.
[0013] Additional objects, advantages and novel features of the
examples will be set forth in part in the description which
follows, and in part will become apparent to those skilled in the
art upon examination of the following and the accompanying drawings
or may be learned by production or operation of the examples. The
objects and advantages of the present subject matter may be
realized and attained by means of the methodologies,
instrumentalities and combinations particularly pointed out in the
appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The drawing figures depict one or more implementations in
accord with the present teachings, by way of example only, not by
way of limitation. In the figures, like reference numerals refer to
the same or similar elements.
[0015] FIG. 1 illustrates an example of a lighting system including
a remote RFID reader, a luminaire incorporating a number of RFID
antennas that are coupled to the RFID reader, and a responsive
device.
[0016] FIG. 2 illustrates a functional block diagram example of an
RFID reader usable in a lighting system, such as the lighting
system examples of FIGS. 1, and 3-5.
[0017] FIG. 3 illustrates an example of a lighting system including
a number of luminaires, an RFID reader internal to one of the
number of luminaires, and a responsive device.
[0018] FIG. 4 illustrates another example of a lighting system that
includes a number of luminaires, a remote RFID reader, and a
responsive device.
[0019] FIG. 5 illustrates an asset tracking system incorporating a
number of lighting systems.
[0020] FIG. 6 illustrates another example of a lighting system
configuration illustrating example communications with a responsive
device.
[0021] FIG. 7 is a flowchart illustrating a process example that
utilizes a lighting system such as any of those shown in FIGS.
1-6.
[0022] FIG. 8A is a flowchart illustrating a system process
example, based on a different signal attribute than that described
relative to FIG. 7.
[0023] FIG. 8B is a flowchart illustrating a process performed by a
responsive device when participating in the system process
described with respect to FIG. 8A.
[0024] FIG. 9 is a flowchart of another example of a process that
may be performed by an RFID enabled lighting system.
[0025] FIGS. 10A to 10I illustrate examples of various diffusers
with associated RFID antennas.
[0026] FIGS. 11A to 11F illustrate examples of various luminaire
housings with associated RFID antennas.
[0027] FIG. 12 is a functional block diagram of a computing device
that may operate as a backend server, a processor, a computer, a
gateway or the like.
[0028] FIG. 13 is a functional block diagram of a passive RFID
tag.
[0029] FIG. 14 is a functional block diagram of an RFID
transceiver, suitable for use in the RFID reader example of FIG.
2.
DETAILED DESCRIPTION
[0030] In the following detailed description, numerous specific
details are set forth by way of examples in order to provide a
thorough understanding of the relevant teachings. However, it
should be apparent that the present teachings may be practiced
without such details. In other instances, well known methods,
procedures, components, and/or circuitry have been described at a
relatively high-level, without detail, in order to avoid
unnecessarily obscuring aspects of the present teachings.
[0031] A need exists for improvement in enabling cost effective and
accurate asset tag tracking utilizing a regionalized RFID reader
configuration utilizing a distributed set of antennas. Such a
regionalized RFID reader covers a larger region in comparison to an
ordinary RFID reader and antenna combination. The following
discussion explains the structure and function of a regionalized
RFID reader configuration that utilizes a central RFID reader
coupled to a number of antennas dispersed around the RFID reader,
for example, dispersed in one or more luminaires in the general
vicinity of the RFID reader, although the circuitry of the reader
may be located remotely. The dispersed antennas enable a single
RFID reader to emit interrogation signals and receive response
messages over a greater area than a single ordinary RFID reader and
antenna combination. The dispersed antennas array reduces the power
output required to interrogate responsive RF devices over an entire
space as compared to a more limited number of antennas, without
requiring additional RFID readers. In addition, power for a
respective RFID reader may be obtained from a luminaire.
[0032] The term "luminaire" as used herein is intended to encompass
essentially any type of device that processes generates or supplies
light, for example, for general illumination of a space intended
for use of or occupancy or observation, by a person or animal.
However, a luminaire may provide light for use by automated
equipment, such as sensors/monitors, robots, etc. that may occupy
or observe the illuminated space, instead of or in addition to
light provided for an organism. However, it is also possible that
one or more luminaires in or on a particular premises have other
lighting purposes, such as signage for an entrance or to indicate
an exit. In most examples, the luminaire(s) illuminate a space or
area of a premises to a level useful for a human in or passing
through the space, e.g. general illumination of a room or corridor
in a building or of an outdoor space such as a street, sidewalk,
parking lot or performance venue.
[0033] The term "coupled" as used herein refers to any logical,
physical or electrical connection, link or the like by which
signals, data, instructions or the like produced by one system
element are imparted to another "coupled" element. Unless described
otherwise, coupled elements or devices are not necessarily directly
connected to one another and may be separated by intermediate
components, elements or communication media that may modify,
manipulate or carry the signals. For example, system elements may
be coupled for wired or wireless communication.
[0034] Reference is now made in detail to the examples illustrated
in the accompanying drawings and discussed below.
[0035] The example of FIG. 1 illustrates a lighting system 10
including a remote RFID reader 12 and a luminaire 13 incorporating
a light source LS 14 and a number of RFID antennas 16 and 18. In
this example, the light source LS 14 is configured to provide
general illumination light to the space in which the luminaire 13
is located. The RFID antennas 16 and 18 are coupled to the RFID
reader 12. The RFID antennas 16 and 18 may be monostatic antennas,
which means, for example, antenna 16 may be used for transmitting
signals and antenna 18 may be used to receive signals.
Alternatively, one or both of the antennas 16 and 18 may be
bi-static. A bi-static antenna transmits and receives signals. The
drawing also shows a responsive RFID device 22. The RFID reader 12
may be configured to transmit and receive radio frequency (RF)
signals to from and the RFID antennas 16 and 18 using wired
communication channels, wireless communication channels, or both.
The RFID reader 12 may output a message that is emitted
over-the-air via one or both of antennas 16 and 18 as an RF signal
19. The RFID reader 12 may receive signals from a responsive RF
device 22 via one or both of antennas 16 and 18 and the couplings
between the reader 12 and the antennas 16, 18.
[0036] The responsive RF device 22 may be located in or traversing
through the space 88. In this example, the responsive RF device 22
may be configured to respond to RF signals 19 transmitted by the
RFID reader 12 by emitting a reply message 29. The reply message 29
may be received by either antenna 16 or 18, or both. The responsive
RF device 22 may be a passive RFID tag that is powered by the
energy received from RF signal 19. For example, when an antenna
(not shown in this example) of responsive RF device 22 receives RF
signals, such as 19, form antennas 16, 18 some of the energy in the
RF signals is converted by circuitry (described in more detail with
reference to FIG. 13) into direct current (DC) electrical power.
While only one responsive RF device 22 is shown, multiple
responsive RF devices may be powered by the RF energy in the RF
signals, such as 19, emitted by antenna 18 and/or 16. For example,
the antennas 16 and 18 may emit RF energy omnidirectionally. Hence,
at least theoretically, even devices not in the space may be
receiving the power. As such, if a single antenna were to emit RF
signals, there may be sufficient RF energy in the emitted RF
signals to supply power for multiple tags, so increasing the number
of antennas should increase the power density. In the examples, the
emitted signals may have sufficient power that the received RF
energy may supply power to multiple tags from the signals emitted
from a single antenna, multiple antennas to a single tag or any
variation thereof. Alternatively, the responsive RF device 22 may
be an active RFID tag that includes a suitable power source.
[0037] In this example, the RFID reader 12 is located remotely from
the luminaire 13. In other examples, the RFID reader may be
collocated with the luminaire 13, for example, by being
incorporated into a housing, or otherwise, integrated into the
luminaire 13.
[0038] The antennas 16 and 18 are configured for wireless radio
frequency communication within the space 88 and may be specifically
adapted (e.g. sized and shaped) for effective wireless
communication at the frequency or frequencies used for the RFID
functions. In addition to the sizing and shape of the antennas 16
and 18, the spacing of the antennas with respect to one another and
the respect to the housing of the light fixture may also be
considered. For example, the spacing of the antennas may be
dependent on the metallic characteristics of the fixture, and may
be considered when multiple antennas are within a fixture. Since
some RFID systems can resolve distances to approximately 10 cm, it
may be more optimal to space the antennas 16 and 18 at least
approximately 10 cm apart. In addition or alternatively, a metal
housing of a lighting fixture may be used to the benefit of the
respective antenna depending upon the characteristics (e.g.,
curvature) of the housing at or near the location of the respective
antenna 16 and/or 18.
[0039] The space 88 may be an indoor location, such as a factory, a
warehouse, a restaurant, an arcade, a retail establishment, an
office, a school, a hospital, an outdoor location, such as a
parking lot, amusement park, a carnival game area, or a combined
indoor/outdoor location, such as an amphitheater, big-box garden
center or the like.
[0040] At a high level, the RFID reader transmits an RFID intended
recipient message from at least one of the antennas 16, 18 and
receives a responsive RFID reply message from a device 22 within
the space 88 via some or all of the antennas 16, 18. The RFID
reader 12 determines a signal attribute of each reply message
signal received via one of the antennas 16, 18. The determined
signal attributes of the reply message signals received via the
antennas 16, 18 and information about locations of the receiving
antennas 16, 18 are processed to estimate a position of the device
22 within the space 88. Examples of signal attributes may include
received signal strength, angle of arrival, angle of departure,
signal phase, time of arrival, time of departure, or the like.
[0041] Additional details of the system 10 operation and details of
the RFID reader 12 and responsive RF device 22 are described with
reference to the examples of FIGS. 2-4, 6 and 10. It may be
appropriate at this time to discuss an example of an RFID reader
suitable for use with a lighting system incorporating antennas at
different separated locations relative to the space within which
the system will estimate the position of a particular responsive
RFID device.
[0042] FIG. 2 illustrates a functional block diagram example of an
RFID reader 280 usable in a lighting system, such as the lighting
system examples of FIGS. 1 and 3-5. The RFID reader 280 in this
example includes a reader processor 282, a memory 283, an
additional data storage device 284, a communication interface
(labeled "comm. inter.") 281, an RFID reader transceiver 285, and a
selectively controllable antenna interface 290.
[0043] The reader processor 282 is coupled to each of the memory
283, the data storage 284, the communication interface 281, the
RFID reader transceiver 285, and the antenna interface 290. An
example of the RFID reader processor 282 may include a data
communication interface or input/output (I/O) for packet data
communication. The processor may be a central processing unit
(CPU), in the form of circuitry forming one or more processors, for
executing program instructions. The processor hardware typically
includes an internal communication bus, and program and/or data
storage for various programs. In addition, or alternatively, the
processor 282 may include couplings to the communication interface
281 for communication with a computing device, such as 229; and
communication ports to the RFID transceiver 285 and/or the
selectively controllable antenna interface 290. The foregoing
processor 282 description is provided by way of example and is not
intended to be the only configuration envisioned. Of course, other
configurations and circuitry may be used to implement the functions
and operations of the disclosed examples.
[0044] The reader processor 282 of FIG. 2 is configured to control
operation of the radio frequency identification reader 280, for
example, based on executable software or firmware program code.
Although the reader processor 282 may be a separate circuit (e.g. a
microprocessor), in many cases, it is feasible to utilize the
central processing unit (CPU), communication interface and
associated memory and data storage of a micro-control unit (MCU)
integrated together as a system on a chip (SOC), as the elements
282, 281, 283 and 284 shown in FIG. 2. More recently, the SOC chip
may also incorporate transmitter and receiver circuity forming a
wireless transceiver, such as the RFID transceiver 285. Such an SOC
with the transceiver can implement the wireless communication
functions as well as the intelligence of the RFID reader 280.
[0045] The antennas E1-E4 may be configured to receive RF signals
in the frequency ranges, such as 900-930 MHz or the like. The
antennas E1-E4 may be individually located in respective luminaires
(not shown in this example), or may be paired in respective
luminaires (as shown in the examples of FIGS. 1, and 3-6.
[0046] The reader processor 282 may, for example, be configured to
perform signal processing of signals received via the antenna
interface 290 as well as being configured to control operation of
the various components and perform the various functions of the
RFID reader 280 described herein. Programming instructions of the
reader processor 282 may be stored in the memory 283 or may be
implemented in firmware (not shown) of, or coupled to, the
processor 282. In addition, the memory 283 or the data storage 284
may be configured to maintain records of determined reply message
attributes corresponding to signals received by each respective
antenna. For example, a record in memory 283 or data storage 284
may contain determined attributes of reply messages corresponding
to each respective antenna, such as antennas 16 and 18 of FIG.
1.
[0047] The antenna interface 290 is coupled to the RFID reader
transceiver 285, and is also selectively coupled to each antenna of
the plurality of luminaires (not shown in this example) within the
space. In some examples, the antenna interface 290 may be a
controllable switch coupled to the processor 282 via a control
signal path 276 that is configured to respond to a selection signal
from the processor 282 to select an antenna for signal transmission
and/or reception. Alternatively, the antenna interface 290 may be
configured as an integrated component of the RFID transceiver 285.
In such a configuration, the processor 282 may send an antenna
selection signal to the RFID transceiver 285 either separately or
as part of a data packet that includes the signals for transmission
or instructions to receive signals. For example, the processor 282
interacts via the RFID transceiver 285 with the antenna interface
290 to select an antenna for signal transmission and/or reception.
The antenna interface 290 may include a number of RFID antenna
connectors, such as 291, 292, 293, and 294, and circuitry and/or a
mechanism that enables selection of a respective antenna, such as
E1, E2, E3 or E4, located at/in one or more luminaires (not shown
in this example) within the space illuminated by the particular
lighting system. For example, the antenna interface may, in
response to control signals, such as an antenna selection signal,
received from the reader processor 282, select a particular RFID
antenna connector for coupling an antenna, such as, for example,
E1, to the RFID reader transceiver 285. Upon coupling the
particular RFID antenna connector to the RFID reader transceiver
285, at the least one selected antenna, such as E1, of the antennas
E1-E4 is communicatively coupled to the reader transceiver 285. The
RFID reader transceiver 285 may be coupled to the RFID antennas in
all the luminaires (not shown in this example) via the antenna
interface 290. The antennas E1-E4 may be associated with individual
luminaires, or may be coupled in pairs, such as antennas E1, E2 in
one luminaire and antennas E3, E4 in another luminaire. The
antennas E1-E4 may be monostatic or bi-static. Alternatively, the
antennas E1-E4 may be multi-static, in which case, the collocated
antennas E1-E4 may provide greater signal strength determination
accuracy and improved localization of a responsive RF device (not
shown in this example). In the example of FIG. 2, only four
connectors 291-294 are shown but the antenna interface 290 may be
configured with more or less connectors, and the processor 282 may
also be configured to selectively switch between the more or less
connectors.
[0048] The data storage device 284 may be configured to store the
unique identifier for each respective antenna of the number of
antennas. The data storage device 284 may be a hard disk drive
(HDD), a solid-state memory device (SSD), a flash memory or
erasable electronic programmable read only memory (EEPROM) or the
like.
[0049] The communication interface 281 is configured to enable the
reader processor 282 to communicate with a server, gateway and/or
other computing device 299 via wired or wireless connections. For
example, the communication interface 281 may be coupled to a
communication media in compliance with one or more communication
protocols and/or specifications, such as EPC Radio-frequency
Identity Protocols Generation 2 UHF RFID, Ethernet, Bluetooth,
Wi-Fi, ZigBee and/or the like. As described in other examples, the
server, gateway and/or computing device 299 may provide services,
such as location determination services, asset tag identification
services, inventory management services, mapping services or the
like. For example, the computing device 299 may forward messages to
the RFID reader 280 that are converted to packets for transmission
as messages or signals, such as an RFID intended recipient message
or the like.
[0050] The reader radio frequency transceiver 285 may be configured
to emit a radio frequency signal (within a specific range, such as
approximately 30 kHz-300 kHz, 3-30 MHz, or 300 MHz-3 GHz, or
another frequency range depending upon the application) from an
antenna selected from the plurality of antennas, and receive reply
messages (also within the approximate frequency ranges of
approximately 30 kHz-300 kHz, 3-30 MHz, or 300 MHz-3 GHz) in
response to the emitted signal.
[0051] The reader processor 282 may be configured to control
operation of the radio frequency identification reader 280. For
example, the RFID reader processor 282 may be configured to cause
the RFID reader transceiver to transmit at least one RFID intended
recipient message from at least one of the antennas (described in
more detail with reference to another example) and to receive, via
one or more of the RFID antenna connectors 291-294, a responsive
RFID reply message from a recipient device (described in more
detail with reference to another example) within the space via a
plurality of the antennas.
[0052] The RFID reader processor 282, may for each antenna coupled
to a respective one or more of the RFID antenna connectors 291-294,
may control the selectable antenna interface 290 to selectively
couple a respective antenna to the reader transceiver 285. The RFID
reader processor 282 may also control the reader transceiver to
transmit an intended recipient message from the respective one
antenna to an intended recipient device. In some examples, the
transmitted intended recipient message may contain the unique
identifier of the respective one antenna and an address of the
intended recipient device within the space, and/or other
information. In other examples, the transmitted recipient message
may only contain the address of the intended recipient device, or
may contain the address of the intended recipient device and/or the
other information. In response to the transmitting of the intended
recipient message, the RFID processor 282 may receive, via the
respective one antenna a reply message from the intended recipient
device.
[0053] In addition, the RFID reader processor 282 may also be
configured to obtain or determine a signal attribute of a reply
message signal received via each antenna of the plurality of
antennas; and process the obtained or the determined signal
attributes of the reply message signals received via the plurality
of antennas and information about locations of the plurality of
antennas to estimate a position of the recipient device within the
space. Examples of the signal determination and processing of the
determined signal attributes of the replay message are described
with reference to other figures such as FIGS. 6-9.
[0054] The RFID reader processor 282 may maintain a record in the
data storage device for each iteration, the record including the
obtained signal attribute in association with the unique identifier
of the respective one antenna and the intended recipient address.
From the records, the RFID reader processor 282 may, for example,
retrieve a received signal strength indication value corresponding
to the measured received signal strength of the received reply
message.
[0055] It may be helpful to describe a system example that includes
a luminaire, such as the luminaire example of FIG. 1 and an RFID
reader, such as the RFID reader example of FIG. 2. FIG. 3
illustrates an example of a lighting system 200 including a number
of luminaires 211-215, an RFID reader 220 internal to one of the
number of luminaires 211-215, and a number of responsive RFID
devices 242 and 244. A gateway controller or server 277 is
communicatively coupled to the RFID reader 220. The server 277 may,
for example, provide messages for communication by the RFID reader
as RFID signals that are received and responded to by one or more
of the responsive devices 242 in the number of RFID devices 244 in
the space 275. For example, the RFID signals may be specifically
addressed signals intended for reception by an intended recipient
device among the number of RFID devices 244 in the space 275. In a
specific example, the intended recipient device may be responsive
RFID device 242 and the specifically addressed signal may be
referred to as an intended recipient device message.
[0056] In addition, the server 277 may, for example, include a
processor and programming that configures the server 277 to
functions such as perform distance estimates/determinations between
a responsive RFID device and a respective antenna based on signal
attributes measured, determined by signals received by the
respective antennas 221A-4225B, or the like. The server 277 may
also be coupled to a data storage, such as 278.
[0057] In the FIG. 3 example, the system 200 includes a number of
luminaires located within a space 275. Each luminaire of the number
of luminaires 211-215 includes a light source, such as LS
202-LS204, and an antenna, such as 221A-225B.
[0058] Each of the light sources LS 202-LS 204 is configured to
provide general illumination light, to the space 275. For example,
light source LS 203 of luminaire 211 is configured to output
general illumination light 251, while light source LS 204 of
luminaire 213 is configured to output general illumination light
252.
[0059] In the example, at least one of the luminaires 211-215 has
an RFID reader 220 internal to the luminaire. Specifically, in the
example of FIG. 3, the RFID reader 220 is shown internal to
luminaire 213. The RFID reader 220 of FIG. 3 is internal to
luminaire 213, but similar to the RFID reader of FIG. 2. For
example, while not shown in the example of FIG. 3, the RFID reader
220 may include a reader processor, and a reader radio frequency
transceiver. As in the example of FIG. 2, the RFID reader 220 of
FIG. 3 is communicatively coupled to an antenna interface 229. The
antenna interface 229 may be either internal or external to the
RFID reader 220. The RFID reader 220, in this example is collocated
with one luminaire, in this example, luminaire 213 of the number of
luminaires 211-215. In this example, the antenna interface 229 may
also be collocated with the luminaire 213.
[0060] The example luminaires in FIG. 3 are shown with two
antennas, but each of the respective luminaires 211-215 may
incorporate more or less antennas depending upon a variety of
reasons, such as RF propagation factors, space propagation factors,
standard compliance reasons or the like. Each antenna 221A-225B may
be configured for wireless radio frequency communication within the
space at a particular radio frequency range. The RFID reader 220
may assign a unique identifier to each antenna 221A-225B. Each
antenna 221A-225B may be communicatively coupled to the antenna
interface 229. For example, luminaire 211 has antennas 221A and
221B. The antennas 221A and 221B are coupled to the antenna
interface 229 via communication media 231A and 231B. Similarly, the
antennas 222A and 222B of luminaire 212 are coupled to the antenna
interface 229 via communication media 232A and 232B, the antennas
223A and 223B of luminaire 213 are coupled to the antenna interface
229 via communication media 232A and 232B, the antennas 224A and
224B of luminaire 214 are coupled to the antenna interface 229 via
communication media 234A and 234B, and the antennas 225A and 225B
of luminaire 215 are coupled to the antenna interface 229 via wired
connections 235A and 235B. The respective wired connections
231A-235B between the antenna interface and the respective antennas
221A-235B may be coaxial cables, Ethernet cables, twisted copper
pairs, fiber optic cable, or the like. Due to a desire for
accuracy, the specifications and electrical properties of the wired
connections as well as any ancillary items such as opto-electrical
converters, amplifiers, connectors, splices or the like may be
determined. For example, the specifications may include the length
of wired connection, and the electrical properties may include
impedance value per foot or meter, material content, or the like.
To maintain consistency of any measurements of the signal
attributes that are made at the RFID reader 220, the communication
path between the respective antennas 421A-425B and the RFID reader
220 is easily maintained and modeled to account for any signal loss
or the like. In other words, there are no sources of interference
or arbitrary signal loss bin the communication path between the
respective antennas 421A-425B and the RFID reader 220 formed by the
wired connections 431A-435B.
[0061] In general, the RF response device 242 and other responsive
RF devices 244 may be "passive" devices each be configured to use
the energy from received signals for power to generate and send a
response to inquiries received via RF signals from the respective
antennas 221A-225B. Alternately, the responsive RF devices 242 and
244 may be "active" devices that have a power supply such as a
battery, solar cell or the like. Regardless of whether the
responsive RF device is a passive or active device, the responsive
RF devices 242, 244 are each configured with an address or
identifier that uniquely identifies the responsive RF device 242
from the other RF response devices 244. The unique identifier or
address allows communications from the RFID reader 220 to be
specifically addressed to a respective one of the responsive
devices 242, 244, in which case the specifically addressed
responsive device is an intended recipient of the communication
signals transmitted by the RFID reader 220 are described in more
detail with reference to later figures.
[0062] Other system configurations are also envisioned. In another
example, the system illustrated in FIG. 4 is an example of a
lighting system that includes a number of luminaires, at least one
responsive device, but with an RFID reader that is remote from a
luminaire. In the example of FIG. 4, each of the luminaires 411-415
may be configured substantially exactly alike. For example, using
luminaires 411 as a model, the luminaire 411 may include antennas
421A and 421B, and a light source LS 104. The other luminaires
412-415 in this example are configured in a similar manner as
luminaire 411. For example, the light sources LS104 of each of the
number of luminaires 411-415 may be configured to provide general
illumination light to the space 375. The light sources LS 104
provide general illumination light to the space 375.
[0063] In addition, instead of the RFID reader being collocated
with a luminaire, such as RFID reader 220 of FIG. 3, the RFID
reader 430 in the example of FIG. 4 is located remotely from the
plurality of luminaires 411-415. Each of the luminaires 411-415 may
have a number of antennas integrated in, coupled to, or collocated
with the respective luminaire. For example, luminaire 412 is shown
with antennas 422A and 422B, and luminaire 415 is shown with
antennas 425A and 425B. Each of the antennas 421A-425B of all the
luminaires 411-415 may have an assigned identifier that uniquely
identifies the respective antenna in the group of antennas
421A-425B. Each of the antennas 421A-425B may be configured for
wireless radio frequency communication within the space 375.
[0064] The antennas 421A-425B of the respective luminaires 411-415
are communicatively coupled to the antenna interface 429 via wired
connections 431A-435B. The antenna interface 429 is coupled to the
RFID reader 430 that allows the RFID reader 430 to send messages
for transmission by one or more of the antennas 421A-425B. For
example, the antenna interface 429 may be a selectable antenna
interface, such as antenna interface 290 of FIG. 3, and may be
configured to couple to each respective antenna 421A-425B of the
number of luminaires 411-415 within the space 375 in response to an
inputted antenna selection signal. In some examples, when an
antenna is selected for transmitting signals from and receiving
signals for the RFID reader 430 via the antenna interface 429, the
selected antenna is referred to as the "currently active" antenna.
More details of an example of selectable antenna interface 429 is
provided with respect to other examples.
[0065] The respective wired connections 431A-235B between the
antenna interface 429 and the respective antennas 421A-425B may be
coaxial cables, Ethernet cables, twisted copper pairs, fiber optic
cable, or the like. Due to a desire for accuracy, the
specifications and electrical properties of the wired connections
as well as any ancillary items such as opto-electrical converters,
amplifiers, connectors, splices or the like may be determined. For
example, the specifications may include the length of wired
connection, and the electrical properties may include impedance
value per foot or meter, material content, or the like.
[0066] A gateway controller or server 488 is communicatively
coupled to the RFID reader 430. The server 488 may, for example,
provide messages for communication by the RFID reader 430 as RFID
signals that are received and responded to by one or more of the
responsive devices 442 of the number of responsive RF devices 444.
The server 488 may, for example, include a processor and
programming that configures the server 488 to perform functions,
such as distance estimates/determinations between a responsive RF
device and a respective antenna based on signal attributes measured
or determined by signals received by the respective antennas
421A-425B. The server 488 may also be coupled to a data storage,
such as 489.
[0067] While the lighting systems 200 and 400 are shown having five
luminaires, the lighting systems may have additional luminaires.
For example, the lighting system may have six, eight or more
luminaires. Of course, fewer luminaires may be included in the
lighting system. It is also envisioned that a number of lighting
systems may be cascaded together to form an asset tracking
system.
[0068] An example of such an asset tracking system is described
with reference to FIG. 5. FIG. 5 illustrates an asset tracking
system incorporating a number of lighting systems.
[0069] In the example of FIG. 5, the system 500 may include number
of luminaires are a subset of a larger group of luminaires.
Lighting systems 550, 560, 570 and 580 may be lighting systems such
as those described with reference to FIGS. 3 and 4, and may be
located within space 590. Each of the lighting systems 550, 560,
570 and 580 may include a number of luminaires coupled to a
respective RFID reader. For example, the lighting system 580
includes luminaires 583, 585, 587 and 589 that are coupled to RFID
reader 537. The luminaires 581-589 of lighting system 580 is a
subset of the larger group of luminaires in the lighting systems
550, 560 and 570. The luminaires of each respective lighting system
550, 560, 570 and 580 are coupled to a different RFID reader. For
example, luminaire 582 of lighting system 580 is coupled to RFID
reader 537, while luminaire 561 is coupled to RFID reader 567. Each
of RFID reader 557, 567, 577, and 537 in each respective lighting
system 550, 560, 570, and 580 may be coupled to a server, or
computing device 520. The RFID readers 557, 567, 577, and 537 may
be networked together in different configurations, such, for
example, as the centralized network configuration shown in FIG. 5,
a mesh configuration or other network configuration. The server 520
may receive information regarding signals received from each
respective responsive RF device 542 and 534. For example, the
server 520 may be configured, for example, to retrieve determined
attributes for reply messages received from respective responsive
RF devices 542 or 534, and estimate or determine a location within
the space from which the received reply message was
transmitted.
[0070] The computing device 520 may similarly be connected to a
computer device 510. The computing device 510 may be a cloud
computing device, a server or the like. The computing device 510
may be configured to assist the server 520 in performance of the
location estimation service or provide data storage or other
services to the server 520.
[0071] FIG. 6 illustrates another example of a lighting system
configuration illustrating example communications with a responsive
RF device. The lighting system 600 may be located in space 610.
Also, located in space 610 may be one or more responsive RF
devices, such as 620 and 625, that are configured to communicate
with the luminaires 611, 613, 615 and 617 of the lighting system
600. The respective luminaires 611, 613, 615, and 617 of lighting
system 600 may each include one or more antennas (1A, 1B, 2A, 2B,
3A, 3B, 4A, 4B, 5A, 5B, respectively), a light source (611A, 613A,
615A, 617A, 619A). The one or more antennas are coupled to an RFID
reader 645. When the lighting system 600 is installed, each of the
respective luminaires 611, 613, 615 and 617 may be positioned at a
known location, such that an antenna on each of the respective
luminaires is also at the known location. Alternatively, the known
locations of the respective antennas may be determined after
installation by utilizing a number of location determination
techniques that may be used in a commissioning process that
commissions the respective antennas into a network of devices. In
the example of FIG. 6, the locations of the antennas 1-5 of the
respective luminaires 611, 613, 615, 617 or 619 of lighting system
600 within space 610 are known. For example, antennas 1A, 1B may be
approximately at location (0,0), antennas 2A, 2B may be
approximately at location (0,5), antennas 3A, 3B may be
approximately at location (3,3), antennas 4A,4B may be
approximately at location (5,0), and antennas 5A, 5B may be
approximately at location (5,5). The approximate location of the
responsive RF device 620 may be determined using the known
approximate locations of the respective antennas 1A-5B.
[0072] The RFID reader 645 may be configured in substantially the
same manner as RFID reader 280 of FIG. 2. For example, the RFID
reader 645 may be communicatively coupled to a server 699. The
server 699 may be configured with a processor and/or memory (not
shown in this example). The server 699 may provide control signals,
such as antenna identifiers, or the like, and also provide services
such as location estimation/determination services. For example,
the server 699 may process signal attribute measurements or signal
attribute-related data for, in combination with, the RFID reader
645. The RFID reader 645 may transmit a signal that is an intended
recipient message specifically addressed to responsive RF device
620. For example, as shown by the dashed lines traversing from
respective antennas 1A, 2A, 3A, 4A, and 5A, toward the responsive
RF device 620, intended recipient messages transmitted as radio
frequency signals may be transmitted individually (e.g., intended
recipient message transmitted iteratively from antenna 1A, then
antenna 2A, then antenna 3A, and so on), simultaneously (e.g. all
antennas 1A-5A transmit an intended recipient message) and/or as
groups (e.g., intended recipient message transmitted simultaneously
only by, for example, antennas 1A and 3A, then followed by intended
recipient message transmitted by antennas 2A and 4A). The
transmitted intended recipient message contains the unique
identifier of the selected antenna and an address of the intended
recipient device (i.e., 620) within the space 610. In response to
receiving the intended recipient message from an antenna, the
responsive RF device 620 may determine it is an intended recipient
device based on a comparison of the address in the intended
recipient message to the responsive RF device's address (or
identifier). In response to the determination by the responsive RF
device 620 that it is the intended recipient device, responsive RF
device 620 may respond with a radio frequency reply message that is
received at the antenna (e.g., antenna 1A) that transmitted the
intended recipient message received by the responsive RFI device
620. Alternatively, in response to the transmitting of the intended
recipient message, the reply message from the intended recipient
device 620 may be received at least one of the respective one or
more antennas 1A-5B, which may or may not include the antenna that
transmitted the intended recipient message (e.g. antenna 1A). In
circuitry (not shown) either coupled to the receiving antenna in
the luminaire (e.g., 611 if the receiving antenna is antenna 1A) or
at the RFID reader 645, an attribute of the received reply message
is measured or calculated that may be used to determine the
location of the responsive RF device 620. For each iteration, a
record may be maintained in a data storage device (not shown in
this example) associated with the RFID reader 645 or server 699.
The record may include the obtained signal attribute in association
with the unique identifier of the selected antenna and the intended
recipient address.
[0073] Responsive RF device 625 may also be receive the intended
recipient message transmitted from the RFID reader 645. However,
the responsive RF device 645 may determine that it is not the
intended recipient device of the intended recipient message, and
may, for example, return to a prior state before receiving the
intended recipient message.
[0074] It may be appropriate to describe with greater specificity
examples of the signal exchange between an RFID reader, such as 645
and a responsive RFID device, such as 620, with reference to the
flowcharts of the examples shown in FIGS. 7-9. As described in the
examples, the exchanged signals are used to determine the location
of the responsive RFID device.
[0075] FIG. 7 is a flowchart illustrating a process example that
utilizes a lighting system such as that shown in FIGS. 1-6, The
process 700 is described with reference to the system components
illustrated in the example of FIG. 6. The responsive RFID devices,
or tags, described in the example of FIG. 7 may be either active or
passive tags.
[0076] The process 700 is also an iterative process. Since there
are a number of antennas, such as antennas 1A-5B, and each antenna
of antennas 1A-5B may or may not be selected as a selected antenna
to transmit an intended recipient message to the same intended
recipient, the following steps 710-760 may be repeated for each
antenna that is selected for transmission of an intended recipient
message to the same intended recipient.
[0077] At the start of the process 700, an RFID reader, whether
collocated with a luminaire (as in the example of FIG. 3) or
located remotely (as in the examples of FIGS. 4 and 6), is coupled
to one or more of a number of antennas for communication purposes,
such as transmission of an intended recipient signal and reception
of a reply message. In addition, the RFID reader, such as 645,
generates an RFID packet for transmission (710). The RFID packet
may, for example, include an address of an intended recipient
device within the space and a unique identifier of the respective
one (or more) antenna(s) selected (i.e., selected antenna(s)) to
transmit the intended recipient address. For example, the unique
identifier may be a representation of a serial number, such as
123ABC456X, and the intended recipient device address may be a
representation of an address, such as MM:MM:MM:SS:SS:SS,
"responsive RFID device 620," or the like. The form of the packet
may follow specific guidelines, such as EPC.TM. Radio-Frequency
Identity Protocols Generation-2 UHF RFID or the like. An RFID
transceiver, not shown in the example of FIG. 6, but such as 285 of
FIG. 2, may be coupled to the RFID antennas 1A-5B in the
luminaires, such as 611, 613, 615, 617 and/or 619 of FIG. 6 in a
lighting system, such as 600. The RFID transceiver emits a signal
with the contents of the generated packet. The generated packet
contents encompassing the RFID intended recipient message. The
emitted RFID intended recipient message is transmitted from at
least one antenna in a respective one of the number of luminaires
in the lighting system (720). At 730, one or more various
responsive RFID devices in the space 610 receive the RFID intended
recipient message wirelessly transmitted from the at least one
antenna. The specific responsive RFID device (also referred to as a
"tag") that has the address of the intended recipient device is one
of the one or more various responsive RFID device that receives the
intended recipient message. Each responsive RFID device is
configured with logic circuitry and memory (described in more
detail with respect to the example of FIG. 13). The memory may, for
example, store an address of the responsive RFID device. After
wirelessly receiving the emitted RFID intended recipient message,
for example, each tag is configured to determine whether it is the
intended recipient device by comparing the address in the intended
recipient message to an address stored in memory of the tag. For
example, the specific responsive RFID device that is the intended
recipient device determines that the address of specific responsive
RFID device is the address stored in its memory. Continuing with
the example, in response to the determination that the selected
antenna is addressed to the intended recipient device, a reply
message is generated by the responsive RFID device at 740. The
generated reply message may, for example, include the unique
identifier of the selected antenna and the intended recipient
device address. The generated reply message from 740 may conform to
the EPC.TM. Radio-Frequency Identity Protocols Generation-2 UHF
RFID or another communication protocol.
[0078] In a more specific example, the responsive RFID device or
tag receives the RF signal containing the intended recipient
message, decodes the signal to obtain the RFID intended recipient
message, and parses the RFID intended recipient message to obtain
the address of he intended recipient and the unique identifier that
identifies the transmitting antenna. The responsive RFID device
confirms that the unique identifier in the RFID intended recipient
message matches the specific responsive RFID device's unique
identifier. Upon successful confirmation, the intended recipient
responsive RFID device (i.e. "recipient device"), at 740, responds
with a reply message signal.
[0079] At 750, the emitting antenna receives the responsive RFID
reply message signal from the intended recipient device within the
space. The reply message signal received at the antenna is
forwarded to the RFID reader's processor. At 760, the RFID
processor determines a signal attribute of the reply message signal
(also referred to as "the determined reply message attribute")
received via the selected antenna. Examples of the attribute of the
received reply message is at least one of received signal strength,
phase, time difference of arrival, or the like. The determined
attribute of the received reply message is usable in estimating a
location within the space from which the received reply message was
transmitted. In another example not illustrated in FIG. 7, the RFID
processor if coupled to another of the antennas coupled to the same
or another luminaire may also receive the transmitted reply message
received by those respective antennas. The signal received by the
other antenna may be processed to determine a signal attribute of
that reply message. In the example of FIG. 7, the determined reply
message attribute, or signal attribute, is the received signal
strength indication (RSSI). The use of other types of signal
attributes may be used to determine distances. Signal attribute
examples, such as time of transmission and receipt, phase shift and
the like, are described with respect to the examples of FIGS. 8A,
8B and 9.
[0080] Returning to the example of FIG. 7, at 760, the measured
received signal strength of the reply message may have a
corresponding RSSI value, or be represented by an RSSI value. The
received signal strength indication value may be stored in a memory
at the RFID reader, such as 645, or may be forwarded to a server,
such as 488, for storage. Alternatively, or in addition, depending
on centralized server or a number of respective RFID readers within
a space, the respective RSSI values may be either stored at
additional RFID readers or on at the network gateway/server side
(e.g., at 277 in 278 of FIG. 3 or at 488 in 489 of FIG. 4, or 520
of FIG. 5).
[0081] As mentioned above, the process 700 is an iterative process.
In an example of the iterative process, a number of antennas are
iteratively selected by the RFID reader to transmit an intended
recipient message to the address of the intended recipient device
for a predetermined number of iterations, e.g., X. During each
iteration, the intended recipient message may include the address
of the same responsive RFID device, but the antenna identifier may
change in each iteration based on the antenna selected by the RFID
reader to transmit the intended recipient message.
[0082] Of course, various combinations of iterations based on using
the same antenna, different antennas, same luminaire, different
luminaires, same RFID readers and different RFID readers have also
been contemplated. For example, the same antenna may transmit a
number of intended recipient messages each separately addressed to
a different address for an intended recipient device (i.e., a
specific responsive RFID device). In another example, a different
iterative process may be implemented in a system such as that shown
in FIG. 5. In this different iterative process, a different RFID
reader may be used in a subsequent iteration. More specifically, in
an iteration the selected antenna is one of the antennas of the
luminaire 561 of the lighting system 560 and the RFID reader 567
transmits the intended recipient message and processes the reply
message received from the intended recipient device, which may be
in this iteration, responsive RFID device 546. In a subsequent
iteration, the selected antenna may be an antenna of luminaire 581
of lighting system 580, the responsive RFID device 546 may be the
intended recipient device, but the RFID reader 537 transmits the
intended recipient message and processes the reply message received
from the intended recipient device. Other combinations of antennas,
luminaires, RFID readers and/or responsive RFID devices may be used
in one or more iterations of the processes examples described with
reference to FIGS. 7-9, the described process examples are provided
for purposes of illustration and general understanding, and are not
intended to be limiting.
[0083] Returning to the example of FIG. 7, at step 765, it may be
determined that another iteration is required (i.e. "in process").
If it is determined another iteration is required, the process
proceeds from 765 to 767. At 767, another antenna is selected from
the antennas in the group of luminaires, such as an antenna coupled
to the same reader or coupled to a different but nearby reader. For
example, antenna 1A of FIG. 6 may have been the currently active
antenna in a just-completed iteration, while in the subsequent
iteration the RFID reader 645 may have been configured to or
instructed to select antenna 2A of FIG. 6. After an antenna is
selected at 767 to replace the currently active antenna in the next
iteration of the iterative process, the process 700 returns to step
710. Upon the return to step 710, the process steps 710-760 are
repeated as substantially described above except that the intended
recipient message transmitted in this next iteration includes the
unique identifier assigned to the selected, currently active
antenna, e.g., antenna 2A. In other words, the intended recipient
message transmitted in this next iteration includes a different
antenna's unique identifier, but the same intended recipient
address.
[0084] The number of iterations X needed to satisfy the decision at
765 may be 3, 6, 12, all of the antennas in a participating
lighting system, or another number that enables location
estimation/determination accuracy acceptable for a particular
application. For example, if the responsive RFID device being
addressed is attached to/associated with a large object, e.g., a
forklift, a shipping container, a copier, treadmill or the like,
the granularity of the location estimation/determination may be
coarser. Based on the assumption that the greater the number of
iterations, the greater the accuracy of the location
estimation/determination, then the number of iterations may be less
for the coarse location estimation/determination. Conversely, if
the responsive RFID device being addressed is attached
to/associated with a smaller object, such as a wheelchair, a
printer, a basket, a retail store product, a slipper or the like,
the granularity of the location estimation/determination may need
to be finer, then a greater number of iteration may be desired to
provide the finer accuracy. In an example, the number of iterations
may be based on the address or a descriptor (e.g., printer, cargo
container) of the intended recipient device, and as such, the
number of iterations may vary. Alternatively, the number of
iterations may remain fixed, e.g., 3, because this number of
iterations is known to provide sufficient accuracy for a number of
applications.
[0085] When the decision at 765 is "done," thereby indicating the
completion of the number of predetermined iterations of the process
steps 710-760, the process 700 proceeds from step 765 to 770.
[0086] At 770, the measured RSSI values are used to
estimate/determine distance between the antenna and the location
from where the reply message was transmitted. Prior to making the
estimate/determination, records of the number of determined reply
message attributes corresponding to the intended recipient address
may be retrieved from the memory, either the memory of an RFID
reader or from a storage associated with a network gateway/server
coupled to the RFID reader. In more detail, the determined signal
attributes of the reply message signals received via the plurality
of antennas (e.g., the RSSI values) and information about locations
of the plurality of antennas (e.g., coordinate locations (such as
5,0 or 0,0), actual latitude and longitude, or the like) may be
processed by the respective RFID reader or by a network
gateway/server. The processing of the RSSI values and the
information about locations of the plurality of antennas determines
respective distances from each respective antenna to the location
of the space from which the received reply message (that provided
the measured RSSI value) was transmitted. After determination of
the respective distances at 770, the process 700 proceeds to 780.
Using the respective distances, a location within the space of the
recipient device from which transmitted the received reply message
may be estimated/determined (780).
[0087] With regard to the location estimating/determining performed
in step 780, different techniques maybe applied to the respective
determined distances and known antenna locations to
estimate/determine the location from which the received reply
message was transmitted. For example, trilateration techniques may
be applied to determine the location within the space from which
the reply message was transmitted.
[0088] In a specific example, a first, second and third record may
be retrieved from the data storage. The records may correspond to
antennas 1A, 2A and 3A of FIG. 6. A processor in either an RFID
reader 645 or a network gateway/server, such as 699, may determine,
using the obtained attribute in each of the respective first,
second and third records, a distance measure of the intended
recipient device, such as 620 of FIG. 6, from the selected antenna
(e.g., 1A, 2A or 3A) in each of the first, second and third
records. The processor, using the distance measures determined from
each of the first, second and third records and known locations of
the selected antennas of each respective first, second and third
records, may apply trilateration techniques to calculate a position
of the intended recipient device with respect to the selected
antennas of each respective first, second and third records.
[0089] After a location of the recipient device is
estimated/determined in 780, the estimated/determined location of
the recipient device is mapped to an indoor location map or the
like that may be provided to a user device or the like (not shown)
(790).
[0090] Trilateration techniques such as those used techniques to
calculate a position of the intended recipient device may utilize
distances determined from other types of signal attributes obtained
from received reply messages. Examples of different types of signal
attributes are described with respect to FIGS. 8A, 8B and 9.
[0091] FIG. 8A is a flowchart illustrating a process example that
utilizes a lighting system such as that shown in FIGS. 1-6, and
FIG. 8B illustrates a flowchart of an example process that may be
performed by a responsive RFID device when participating in the
process described with respect to FIG. 8A. The process 800 of FIG.
8A and process 801 of FIG. 8B will be described with reference to
the lighting system 600 and responsive RFID device, or tag, 620 of
FIG. 6. The responsive RFID devices, or tags, in the examples of
FIGS. 8A and 8B are more than likely active tags. There may be
passive tags that may be capable of "harvesting" and storing enough
power to perform the functions described with reference to FIGS. 8A
and 8B. Recall that an active tag may either include a power
source, such as a battery, photovoltaic cell or the like, or a
connection to an external power source, such as a battery source, a
transformer of AC main power, or the like.
[0092] Similar to the process 700, the process 800 of FIG. 8A may
be an iterative process. Since there are a number of antennas, such
as antennas 1A-5B, in a lighting system, and each antenna of
antennas 1A-5B may or may not be selected to transmit an intended
recipient message to the same intended recipient, the following
steps 810-860 may be repeated for each antenna that is selected for
transmission of an intended recipient message to the same intended
recipient.
[0093] In the process 800, an RFID reader, whether collocated with
a luminaire (as in the example of FIG. 3) or located remotely (as
in the examples of FIGS. 4 and 6), selects, at 805, one or more of
a number of antennas for communication purposes, such as
transmission of an intended recipient signal and reception of a
reply message. In addition, the RFID reader, such as 645, generates
an RFID packet for transmission (810). The RFID packet may, for
example, include an address of an intended recipient device within
the space and a unique identifier of the respective one (or more)
antenna(s) selected to transmit the intended recipient address.
[0094] The RFID transceiver emits a signal with the contents of the
generated packet. The generated packet contents encompassing the
RFID intended recipient message. The emitted RFID intended
recipient message is transmitted from at least one antenna in a
respective one of the number of luminaires in the lighting system
(815). At 820, one or more various responsive RFID devices in the
space, such as 610, receive the RFID intended recipient message
wirelessly transmitted from the at least one antenna. The specific
responsive RFID device, or tag, that has the address of the
intended recipient device is one of the one or more various
responsive RFID device that receives the intended recipient
message.
[0095] Each of the "active" responsive RFID devices, or "active"
tags, in a space, such as 610, that participate in the process of
the FIG. 8A example, may perform the process 801 of FIG. 8B. Each
participating responsive RFID device may be powered ON using power
from a battery or external power source (891). The ON responsive
RFID device may be in a sleep state or low power mode, in which the
responsive RFID device is waiting to receive a signal from another
RFID device. In the sleep state or low power state, the responsive
RFID device may continue to run a system clock (893) so that it has
a time that is approximately synchronized (e.g. within a tolerance)
with a clock of the RFID reader. The responsive RFID device waits
for an RFID packet containing the intended recipient message at
895. When RFID signals are detected, the logic circuitry of the
responsive RFID device (an example of which is explained in more
detail with reference to FIG. 13) may process the received signal
to determine if an RFID packet of the received signal contain the
intended recipient device (897). Step 895 may be a sub-step related
to step 820 of process 800 of FIG. 8A. When it is determined that
an RFID signal containing the intended recipient message is
received, the process 801 returns to step 825 of process 800 of
FIG. 8A. At 825, the responsive RFID device using the responsive
RFID device's clock may generate a timestamp indicating when the
intended recipient message was received, and process 800 proceeds
to step 830. The responsive RFID device may generate an interim
reply message. The interim reply message may include the timestamp
indicating when the intended recipient message was received, and
the unique identifier of the antenna from which the intended
recipient message was transmitted. The interim reply message may
include additional information, such as the responsive RFID device
address or the like.
[0096] The RFID reader receives the reply message transmitted by
the responsive RFID device that was the intended recipient. In
response to receiving the interim reply message, the RFID reader
responds by transmitting a timestamp acknowledgement (835) and also
generates a timestamp indicating when the timestamp acknowledgement
was sent to the responsive RFID device by the RFID reader.
[0097] In response to receiving the timestamp acknowledgement, the
responsive RFID device generates a timestamp of when the time stamp
acknowledgement was received, and generates a final reply message
that is transmitted to the RFID reader (840). The final reply
message may include a final timestamp indicating when the
acknowledgement was received from the RFID device. The final
timestamp may also include a unique identifier of the antenna from
which the intended recipient message was transmitted. The final
reply message may include additional information, such as the
responsive RFID device address or the like.
[0098] A number of additional process steps may be encompassed in
step 845. For example, in 845, the RFID reader may be configured to
determine a time difference between the RFID reader's timestamp
indicating when the intended recipient message was transmitted and
the interim reply message timestamp (of step 830). In addition, the
RFID reader may be configured to determine a time difference
between the RFID reader's timestamp of the timestamp
acknowledgement message indicating when the timestamp
acknowledgement message was transmitted and the time stamp final
reply message timestamp (of step 840). The RFID reader may be
further configured to average the two determined time differences
or use only one if the determined differences are within a
threshold. The RFID reader may be further configured to use the
determined difference to compute a distance from the selected
antenna that transmitted received the to the responsive RFID
reader. When the distances are determined, the RFID reader may
store the determined distances either in a memory coupled to the
RFID reader (850).
[0099] The process 800 is an iterative process. In an example of
the iterative process, a number of antennas are iteratively
selected by the RFID reader to transmit an intended recipient
message to the address of the intended recipient device for a
predetermined number of iterations, e.g., X. During each iteration,
the intended recipient message may include the address of the same
responsive RFID device, but the antenna identifier may change in
each iteration based on the antenna selected by the RFID reader to
transmit the intended recipient message.
[0100] At step 860, it may be determined that another iteration is
required (i.e. "in process"). If it is determined another iteration
is required, another antenna is selected from the antennas in the
group of luminaires. For example, antenna 1A of FIG. 6 may have
been the currently active antenna in a just-completed iteration,
while in the subsequent iteration the RFID reader 645 may have been
configured to, or instructed to, select antenna 2A of FIG. 6. After
an antenna is selected to replace the currently active antenna in
the next iteration of the iterative process, the process 800
returns to step 810. Upon the return to step 810, the process steps
810-860 are repeated as substantially described above except that
the intended recipient message transmitted in this next iteration
includes the unique identifier assigned to the selected, currently
active antenna, e.g., antenna 2A. In other words, the intended
recipient message transmitted in this next iteration includes a
different antenna's unique identifier, but the same intended
recipient address.
[0101] The number of iterations X needed to satisfy the decision at
860 may be 3, 6, 12, all of the antennas in a participating
lighting system, or another number that enables location
estimation/determination accuracy acceptable for a particular
application.
[0102] When the decision at 860 is "done," thereby indicating the
completion of the number of predetermined iterations of the process
steps 810-860, the process 800 proceeds from step 860 to step
865.
[0103] At 865, the determined differences are used to
estimate/determine a location of the responsive RFID device that is
the recipient device within the space, such as 610. With regard to
the location estimating/determining performed in step 865,
different techniques maybe applied to the respective determined
distances and known antenna locations to estimate/determine the
location from which the received reply message was transmitted. For
example, trilateration techniques may be applied to determine the
location within the space from which the reply message was
transmitted.
[0104] After a location of the recipient device (i.e., responsive
RFID device) is estimated/determined in 865, the
estimated/determined location of the recipient device is mapped to
an indoor location map or the like that may be provided to a user
device or the like (not shown) (870).
[0105] FIG. 9 is a flowchart of another example of a process that
may be performed by a lighting system, such as those in FIGS. 1-6.
retrieve a signal phase representation corresponding to a signal
phase of the received reply message when received by the respective
selected antenna.
[0106] Unlike to the processes 700 and 800, the process 900 of FIG.
9 may not be an iterative process. In the process 900, all of or a
number, such as 3, of the multiple antennas in the lighting systems
described with respect to FIGS. 3-6 may be configured to and
coupled to the RFID reader to simultaneously receive
[0107] In the process 900, an RFID reader, whether collocated with
a luminaire (as in the example of FIG. 3) or located remotely (as
in the examples of FIGS. 4 and 6), selects, at 905, one or more of
a number of antennas for communication purposes, such as
transmission of an intended recipient signal and reception of a
reply message. In addition, the RFID reader, such as 645, generates
an RFID packet for transmission (915). The RFID packet may, for
example, include an address of an intended recipient device within
the space and a unique identifier of the respective one (or more)
antenna(s) selected to transmit the intended recipient address.
[0108] At 920, the RFID transceiver emits a signal with the
contents of the generated packet. The generated packet contents
encompassing the RFID intended recipient message. When the emitted
RFID intended recipient message is transmitted from the at least
one antenna, the signal phase is noted by the RFID reader
processor.
[0109] At 925, various responsive RFID devices, or tags, receive
the transmitted signal containing the intended recipient message
from the selected antenna, and the phase of the received signal is
measured by the responsive RFID device. The various responsive RFID
devices may be active RFID devices. Each of the various responsive
RFID devices may measure the phase of the received signal, and
process the received signal to determine whether the receiving
device is the intended recipient of the message contained in the
signal. If one of the various RFID devices is the intended
recipient device, the responsive RF recipient device responds to
the RFID reader (930). The responsive RF device that is the
intended recipient may generate a data packet containing a reply
message. The reply message that includes the unique identifier of
the antenna that transmitted the intended recipient message.
Alternatively, the reply message may simply be an acknowledgement
message that is broadcast for all antennas of the RFID reader to
receive.
[0110] At 935, the reply message sent from the intended recipient
device is received by multiple antennas coupled to the RFID reader.
The phase of the received signal is calculated at each of the
multiple antennas that received the reply message. The phase of the
transmitted signal measured by the RFID reader is compared to the
calculated phase of the signal received at each of the multiple
antennas that received the reply message (940). Based on the
comparison, a phase difference at each antenna of the multiple
antennas is determined. When determining the phase differences for
each antenna, the antenna cabling distance is taken into accounted
to ensure that the phase difference determination is accurate. At
945, a relative distance difference based on the signal phase
between antennas may be calculated. For example, the shift of the
signal may be compared to the speed of light, thereby comparing
time differences, rather than comparing the actually received
signal to the originally transmitted version. The calculated
relative distance differences and/or other data may be stored in a
memory of the RFID reader (950). Alternatively, or in addition, the
calculated relative distance differences may either be stored at
additional RFID readers (such as in the multiple lighting system
example of FIG. 5 or in a data storage coupled to a server or
network gateway.
[0111] At 955, the calculated relative distance differences are
used to estimate/determine the location of the recipient device
with the space. The distance determination uses known locations of
the luminaires and/or the antennas. For example, the RFID reader,
server or network gateway may be configured to use trilateration of
the distances determined from the phase shift calculations to
determine a location of the recipient device with respect to each
of the antennas. At 960, the determined locations of the recipient
device may be confirmed to be accurate using different techniques,
such as comparing the determined location to a prior location of
the recipient device, identifying values of the determined location
is within the space, the determined location of the recipient
device based on the phase difference calculations from each antenna
is within a predetermined threshold, using known locations from
BLE/Wi-Fi tracking on smart devices, location history of tags
and/or smart devices, using a combination of techniques, such as
RSSI and angle of arrival or TDOA, combine with non-RIFD location
service, or the like. If determination is the locations are not
accurate, the process requires a "Repeat." In the case that a
repeat is necessary, the process 900 returns to 915, and steps
915-960 are repeated. Conversely, if the determination at 960 is
the location are accurate, the process is "Done" and the process
900 continues to 965. At 965, after the estimated/determined
location of the recipient device (i.e., responsive RFID device) is
confirmed as accurate in 960, the estimated/determined location of
the recipient device is mapped to an indoor location map or the
like. The indoor map may be provided to, or accessed by, a user
device or the like (not shown) that monitors the locations of
responsive RFID devices.
[0112] FIGS. 10A to 10G illustrate examples of various diffusers
with associated RFID antennas. In the examples of FIGS. 10A-10G,
each antenna of each respective luminaire of the plurality of
luminaires is collocated with a diffuser of each respective
luminaire. The antennas of FIGS. 10A-10G are not drawn to scale
with regard to the frequencies described herein. For example, in
FIGS. 10A and 10B, the respective associated antennas 1010 and 1011
may be embedded in or attached to the respective diffusers 1000 and
1001. Similarly, the respective associated antenna 1012-1016 may be
embedded in or attached to the respective diffusers 1002-1006. A
respective antenna may be formed from copper, Indium-Tin-Oxide
(ITO), a nano-mesh, such as silver or gold nano-mesh, carbon
nanotubes, or the like. In addition, or alternatively, an antenna
may be formed within layers of a printed circuit board. Each of the
respective antennas 1010-1016 is configured to be used in a
lighting system, such as those described with reference to the
examples of FIGS. 1 and 3-6.
[0113] In FIGS. 10A and 10B, the respective diffusers 1000 and 1001
have curved surfaces. The antenna 1010 of FIG. 10A is arranged to
traverse the curved surface of the diffuser 1000 in a repeated
back-and-forth pattern along a longitudinal axis of the diffuser
1000. The antenna 1011 of FIG. 10B is arranged in the form of a
square wave that extends along a longitudinal axis of the diffuser
1001. Of course, the square wave may be configured differently,
such as having non-uniform peaks or the like. Alternatively, a
different form of wave may be used, such as a sinusoid or a
sawtooth waveform. In contrast to the curved diffuser surfaces of
FIGS. 10A and 10B, the diffuser 1002 of FIG. 10C is circular. The
diffuser 1002 shown in FIG. 10C may be incorporated into a
drop-light-type of light fixture. The circular diffuser 1002 may
have an antenna 1012 arranged in a pattern near a center of the
diffuser 1002. While the diffuser 1002 is shown as a circle, the
diffuser 1002 may be oval shaped. The antennas 1010, 1011 and 1012
may be monostatic antennas.
[0114] FIGS. 10D-10I illustrate examples of rectangular diffusers.
In FIG. 10D, the antenna 1013 may be configured to follow the
rectangular perimeter of the diffuser 1003. Alternatively, other
antenna shapes may be used. Instead of the antenna following the
perimeter of the diffuser as in FIG. 10D, an antenna may be
arranged to follow a portion of the diffuser's perimeter. For
example, the antenna 1014 follows the perimeter of the diffuser
1004 for approximately three-quarters of the perimeter, but extends
toward the center of the diffuser 1004 at some point. The antennas
1013 and 1014 have been shown as having substantially closed
shapes, however, in other examples, diffusers may form an open
pattern. For example, the antenna 1005 may be arranged to extend
about the area of the diffuser 1015. The diffusers 1001-1005 with
antennas 1010-1015 may be paired with another diffuser having an
antenna to provide the antenna pairs shown in the examples of FIGS.
1 and 3-6. In FIG. 10G, separate antennas 1016A-1016D may be
located at different areas of the diffuser 1006, such as in the
corners of the diffuser 1006. The separate antennas 1016A-1016B may
connect separately to an RFID reader or may be connected to the
RFID reader in pairs, such as antenna 1016B paired with antenna
1016C, or in another arrangement. While the antennas 1010-1016B are
shown as heavy dark lines in the figures as compared to the
respective diffusers, it is envisioned that the antennas 1010-1016D
may be transparent, or substantially transparent, in an actual
implementation. For example, the antennas 1010-1016D may be formed
from materials such as indium-tin-oxide, an extra-fine strand
copper, or the like. FIG. 10H illustrates another example of a
diffuser configuration that has multiple antennas 1018A-1018C
integrated therein. The antennas 1018A-C may be configured in a
polygonal shape suitable for transmission of RF signals within a
space. The antennas 1018A-C may be arranged at different locations
along a diagonal axis of the diffuser 1008. The antennas 1018A-C
may be coupled together to emit RF signals simultaneously, or may
be individually coupled to an RFID transmitter for separate RF
signal emissions. FIG. 10I illustrates yet another example
configuration of a diffuser 1009 with integrated antennas 1019A-C.
The antennas 1019A-C may be arranged at different locations within
the diffuser 1009. The antennas 1019A-C may be coupled together to
emit RF signals simultaneously, or may be individually coupled to
an RFID transmitter for separate RF signal emissions.
[0115] FIGS. 11A to 11G illustrate examples of various luminaire
housings with associated RFID antennas. Each of the respective
antennas 1131-1034D is configured to be used in the lighting
systems described with reference to the examples of FIGS. 1 and
3-6.
[0116] FIG. 11A illustrates an example of luminaire 1100 that
includes a housing 1101, an antenna 1131 and light sources 1121A
and 1121B. The antenna 1131 is coupled to the housing 1101, and is
configured to be behind or in front of the light sources 1121A and
1121B. The light sources 1121A and 1121B are configured to provide
general illumination light to the space in which the luminaires are
located.
[0117] FIG. 11B illustrates an example of luminaire 1110 that
includes a housing 1102, an antenna 1132 and light sources 1122A
and 1122B. The antenna 1132 is coupled to the housing 1102, and is
configured to be either behind or in front of the light sources
1122A and 1122B.
[0118] FIG. 11C illustrates an example of luminaire 1120 that
includes a housing 1103, an antenna 1133 and light sources 1123A
and 1123B. The antenna 1133 is coupled to the housing 1103 near the
perimeter of the housing 1103. The antennas 1130 may surround the
light sources 1123A and 1123B so as to not occlude the general
illumination light emitted by the light sources 1123A or 1123B.
[0119] FIG. 11D illustrates an example of luminaire 1130 that
includes a housing 1104, a first antenna 1134A, a second antenna
1134B, a third antenna 1134C, a fourth antenna 1134D, and light
sources 1124A and 1124B. The housing 1104 is rectangular shaped,
but may be other shapes, such as circular, hexagonal or the like.
The four antennas 1134A-1134D may be positioned in the corners of
the rectangular housing 1104. By positioning the four antennas
1134A-1134D in the corners, the antennas 1134A-1134D do not occlude
the general illumination light emitted by the light sources 1124A
or 1124B. Similar to the antennas 1016A-1016D of FIG. 10G, each of
the antennas 1134A-1134D may be separately coupled to an RFID
reader, such as the RFID readers of FIGS. 1 and 3-6. For example,
the separate antennas 1134A-1134D may be connected to the RFID
reader in pairs, such as antenna 1134B may be paired with antenna
1134C, or in another arrangement.
[0120] FIG. 11E illustrates an example of luminaire 1140 that
includes a housing 1105, a first antenna 1145A, a second antenna
1145B, a third antenna 1145C, a fourth antenna 1145D, and light
sources 1125A and 1125B. The housing 1105 is rectangular shaped,
but may be other shapes, such as circular, hexagonal or the like.
The four antennas 1145A-1145D may be positioned at different
locations near the light sources 1125A and 1125B, and may be sized
(e.g. have a diameter) that does not noticeably occlude light
emitted by the light sources 1125A or 1125B. Each of the antennas
1145A-1145D may be separately coupled to an RFID reader, such as
the RFID readers of FIGS. 1 and 3-6. For example, the separate
antennas 1145A-1145D may be connected to the RFID reader in pairs,
such as antenna 1145B may be paired with antenna 1145C, or in
another arrangement.
[0121] While the antennas 1131-1145D of FIGS. 11A-11E, are shown as
heavy dark lines in the figures as compared to the respective
housings 1101-1104, it is envisioned that the antennas 1131-1145D
may be transparent, or substantially transparent, in an actual
implementation. For example, the antennas 1131-1145D may be formed
from materials such as indium-tin-oxide, an extra-fine strand
copper wire, nanowires, or the like.
[0122] FIG. 11F illustrates yet another example of the integration
of an antenna in a luminaire. In the FIG. 11F example, the antennas
1165A and 1165B may protrude out of the plane of the luminaire
1165, instead of on the traces of boards flush on a diffuser 1165.
The antennas 1165A and 1165B may monopole antennas, dipole
antennas, or the like, and be formed from materials such as
indium-tin-oxide, an extra-fine strand copper wire, nanowires, or
the like.
[0123] The foregoing examples of luminaires and the respective
implementations of the luminaires are shown to illustrate only a
few of the contemplated configurations. The following discussion
explains at a high level functional components of the servers, such
as 299 of FIG. 2, 277 of FIG. 3, 488 of FIG. 4 or 510 of FIG.
5.
[0124] As known in the data processing and communications arts, a
general-purpose computer typically includes a central processor or
other processing device, an internal communication bus, various
types of memory or storage media (RAM, ROM, EEPROM, cache memory,
disk drives etc.) for code and data storage, and one or more
network interface cards or ports for communication purposes. The
software functionalities involve programming, including executable
code as well as associated stored data, e.g. files for the
communication device ID codes and associated communication device
positions obtained during commissioning. The software code is
executable by the general-purpose computer that functions as the
configuration server and/or that functions as a mobile device. In
operation, the code may be stored within the server, such as 299 of
FIG. 2, 277 of FIG. 3, 488 of FIG. 4 or 510 of FIG. 5, or a related
data storage. At other times, however, the software code may be
stored at other locations and/or transported for loading into the
appropriate general-purpose computer system. Execution of such
software code by a processor of the computer platform enables the
platform to implement appropriate aspects of the location
estimating/determining of the responsive RF devices, in essentially
the manner performed in the implementations discussed and
illustrated herein.
[0125] For purposes of further discussion, FIG. 12 shows a computer
platform as an example of an implementation of the hardware for a
server configured/programmed as an appropriate servers or network
gateway, such as 299 of FIG. 2, 277 of FIG. 3, 488 of FIG. 4 or 510
of FIG. 5. The server computer includes a CPU for executing program
instructions, such as the appropriate server application
program(s). The computer server platform typically includes an
internal communication bus, program storage, such as memories (ROM
and RAM) and/or data storage DS, for various data files to be
processed and/or communicated by the server, although the server
often receives programming and data via network communications. It
is believed that those skilled in the art are adequately familiar
with the structure, programming and general operation of computer
equipment, such as that shown in FIG. 12, and as a result, the
drawing should be self-explanatory.
[0126] Hardware of a server computer (FIG. 12), for example
(server/gateway/computing device 299 of FIG. 2, 277 of FIG. 3, 488
of FIG. 4 or 510 of FIG. 5), includes a data communication
interface or input/output (I/O) for packet data communication. The
server computer's central processing unit (CPU), in the form of
circuitry forming one or more processors, for executing program
instructions. The server platform hardware typically includes an
internal communication bus, program and/or data storage for various
programs and data files to be processed and/or communicated by the
server computer, although the server computer often receives
programming and data via network communications.
[0127] Reference is now made to FIG. 13, which schematically
depicts an example of a responsive RF device, which may also be
referred to as an RF-enabled asset tag 1304. FIG. 13 is a
functional block diagram of an RFID device. Depending upon whether
the responsive RFID device 1304 is an active tag or a passive tag,
the responsive RFID device 1304 may have different types of
components related to a power source in the case of an active tag
or rectifying circuitry in the case of a passive tag
implementation.
[0128] Radio frequency signal transmissions from one or more
antennas of the lighting system examples described above with
respect to FIGS. 1, 3-11D may be received by one or more tags 1304.
When configured as a passive tag, responsive RFID device 1304
includes an antenna 1360, rectifier circuitry (e.g., a capacitor,
diodes or the like) 1310, reader circuitry 1320, information
processing circuitry 1380, a data storage 1370 (e.g., an
electronically erasable programmable read-only memory (EEPROM))),
and modulation circuitry 330.
[0129] The tag antenna 1360 is capable of both receiving radio
frequency (RF) signals and of transmitting radio frequency signals.
The tag antenna 1360 may be a loop antenna or similar antenna. When
the antenna 1360 receives RF signals some of the energy in the RF
signals is converted by the rectifier circuitry 1360 into direct
current (DC) power. If the received signal has sufficient signal
strength, the converted DC power is sufficient to supply power the
other components of the passive tag 1304. For example, with
sufficient DC power, the information processing circuitry 1380 may
be powered for some interval. The received signal is input to the
reader circuit 1320 which may be configured to process the input
signal to output data representative of the intended recipient
message. The information processing circuitry 1380 includes logic
circuitry (or simply "logic") 1340 and a memory 1350. The memory
1350 may store an address of the tag and other information related
to the tag 1304. Alternatively, the tag address and other
information related to the tag 1304 may be stored in storage
(EEPROM) 1370. The logic 1340 of information processing device 1380
may be configured to perform functions that include the processing
of data received through the antenna 1360 utilizing the logic
circuitry 1340 and transmitting information (e.g., an address of
the tag 1304 retrieved from memory 1350 and the unique identifier
of the luminaire antenna that transmitted the received signal)
through the antenna 1360.
[0130] Functions performed by the information processing device
1380 may include determining that the received intended recipient
message is addressed to the tag device 1304 by comparing the
address in the intended recipient message to an address stored in
memory 1350 of the intended recipient device 1304. After the logic
1340 retrieves the tag address from the memory 1350 or from storage
1370, the logic 1340 may be configured to generate a data packet
that includes the tag address and the antenna identifier. The
generated data packet may be forwarded to the modulation circuitry
1330 which generates a reply message that is transmitted from the
tag 1304.
[0131] In addition, the information processing device 1380 may be
configured to measure received signal strength indicator (RSSI) of
a signal transmitted by an antenna in a luminaire as described
above with reference to FIGS. 1 and 3-6. The RSSI measurement
capabilities of the logic 1340 may be available to the passive
tag.
[0132] If more processing capabilities are needed, the tag 1304 may
be configured to receive DC power from a DC power source 1388. As
an active tag, the logic 1340 may be configured to in response to
receiving the intended recipient message, may perform functions
such as those described with reference to FIG. 8B as well as FIGS.
8A and 9.
[0133] Reference is now made to FIG. 14, which schematically
depicts an example of an RFID schematic a reader processor
configured to control operation of the radio frequency
identification reader;
[0134] The selectable antenna interface 1420 is coupled to an RFID
reader processor, such as processor 282 of FIG. 2. In addition, the
selectable antenna interface 1420 is selectively coupled to each
respective antenna of a number of antennas (not shown in this
example) located within the space via the antenna connectors 1430.
The selectable antenna interface 1420 may be a coupler, a
circulator, or a switch, which couples a respective one or more of
the antenna connectors 1430 to the RFID transceiver 1410. In
response to a selection signal from the RFID reader processor, the
selectable antenna interface 1420 may couple an antenna connector
1430 corresponding to the selected antenna (not shown).
[0135] The reader radio frequency transceiver 1410, for example,
may be coupled to the reader processor and the selectable antenna
interface 1420. The reader radio frequency transceiver 1410 may
include a transmit side 1405 and a receive side 1407. The data
input to the transmit side 1405 of the RFID transceiver 1410 may be
packet data representing the intended recipient message and/or
related information. The RFID transceiver 1410 is configured to
emit a signal representing the intended recipient message and/or
related information from an antenna selected from the number of
antennas coupled via the antenna connectors 1430 to the selectable
antenna interface 1420. The transmit side 1405 may include a
modulator 1411, an up converter 1413, a power amplifier 1415, a
transmit filter 1417. The transmit filter 1417 may be coupled to
the selectable antenna interface 1420 to deliver the RF signals for
transmission from the selected antenna.
[0136] The RFID transceiver 1410 is configured to receive reply
messages in response to the signal emitted by the RFID transceiver
1410 and transmitted from the selected antenna. The received reply
message may be in the form of a signal representing an identifier
of the transmitting antenna and the address of the intended
recipient responsive RFID device. The receive side 1407 may include
a receive filter 1412, a low noise amplifier 1414, a down converter
1416 and a demodulator 1418. The respective components 1411-1418
perform signal processing functions according to their respective
labels. For example, the modulator 1411 modulates the input data
"Data In", and the power amplifier 1415 amplifies the signal output
from the up converter 1413. In addition, the RFID transceiver 1410
is configured to receive reply messages in response to the emitted
signal encompassing the intended recipient message. The received
signal is filtered by the filter 1412, the low noise amplifier 1414
amplifies the low power signal output from filter 1412, and the
demodulator 1418 demodulates the down converted signal output from
the down converter 1416. The data output from the demodulator 1418
of the receive side 1407 may be data representative of the reply
message transmitted by the responsive RF device that was the
intended recipient of the transmitted intended recipient
message.
[0137] The foregoing example is provided for purposes of
illustration and understanding. Of course, other configurations
and/or implementations of an RFID transceiver, a selectable antenna
interface and antenna connectors may be used.
[0138] Aspects of methods of utilizing selected antennas from an
array of antennas to transmit signal to and receive signals from a
responsive RFID device, also referred to as a tag, by the system
and process examples in FIGS. 1-9 described above may be embodied
in programming, e.g. in the form of software, firmware, or
microcode executable by an RFID reader, a responsive RFID device, a
server computer or other programmable device. Program aspects of
the technology may be thought of as "products" or "articles of
manufacture" typically in the form of executable code and/or
associated data that is carried on or embodied in a type of machine
readable medium. "Storage" type media include any or all of the
tangible memory of the computers, processors or the like, or
associated modules thereof, such as various semiconductor memories,
tape drives, disk drives and the like, which may provide
non-transitory storage at any time for the software programming.
All or portions of the software may at times be communicated
through networks that include the RFID readers and/or servers or
network gateways described in the foregoing examples of FIGS. 1-14.
Such communications, for example, may enable loading of the
software from one computer or processor into another, for example,
from a server, RFID reader or gateway computer in the examples
described with reference to FIGS. 1-14. Thus, another type of media
that may bear the software elements includes optical, electrical
and electromagnetic waves, such as used across physical interfaces
between networked devices, through wired and optical landline
networks and over various air-links. The physical elements that
carry such waves, such as wired or wireless links, optical links or
the like, also may be considered as media bearing the software. As
used herein, unless restricted to one or more of "non-transitory,"
"tangible" or "storage" media, terms such as computer or machine
"readable medium" refer to any medium that participates in
providing instructions to a processor for execution.
[0139] Hence, a machine-readable medium may take many forms,
including but not limited to, a tangible or non-transitory storage
medium, a carrier wave medium or physical transmission medium.
Non-volatile storage media include, for example, optical or
magnetic disks, such as any of the storage hardware in any
computer(s), portable user devices or the like, such as may be used
to implement the server computer 510, the computer 520, the
responsive devices 22, 142, 342 or RFID reader 12, 130, 400, 204,
etc. shown in the drawings. Volatile storage media include dynamic
memory, such as main memory of such a computer or other hardware
platform. Tangible transmission media include coaxial cables;
copper wire and fiber optics, including the wires that comprise a
bus within a computer system. Carrier-wave transmission media can
take the form of electric or electromagnetic signals, or acoustic
or light waves such as those generated during radio frequency (RF)
and light-based data communications. Common forms of
computer-readable media therefore include for example: a floppy
disk, a flexible disk, hard disk, magnetic tape, any other magnetic
medium, a CD-ROM, DVD or DVD-ROM, any other optical medium, punch
cards paper tape, any other physical storage medium with patterns
of holes, a RAM, a PROM and EPROM, a FLASH-EPROM, any other memory
chip or cartridge (the preceding computer-readable media being
"non-transitory" and "tangible" storage media), a carrier wave
transporting data or instructions, cables or links transporting
such a carrier wave, or any other medium from which a computer can
read programming code and/or data. Many of these forms of computer
readable media may be involved in carrying data and/or one or more
sequences of one or more instructions to a processor for
execution.
[0140] Program instructions may comprise a software or firmware
implementation encoded in any desired language. Programming
instructions, when embodied in a machine readable medium accessible
to a processor of a computer system or device, render a computer
system or a device into a special-purpose machine that is
customized to perform the operations specified in the program
instructions.
[0141] Unless otherwise stated, any and all measurements, values,
ratings, positions, magnitudes, sizes, and other specifications
that are set forth in this specification, including in the claims
that follow, are approximate, not exact. They are intended to have
a reasonable range that is consistent with the functions to which
they relate and with what is customary in the art to which they
pertain.
[0142] The scope of protection is limited solely by the claims that
now follow. That scope is intended and should be interpreted to be
as broad as is consistent with the ordinary meaning of the language
that is used in the claims when interpreted in light of this
specification and the prosecution history that follows and to
encompass all structural and functional equivalents.
Notwithstanding, none of the claims are intended to embrace subject
matter that fails to satisfy the requirement of Sections 101, 102,
or 103 of the Patent Act, nor should they be interpreted in such a
way. Any unintended embracement of such subject matter is hereby
disclaimed.
[0143] Except as stated immediately above, nothing that has been
stated or illustrated is intended or should be interpreted to cause
a dedication of any component, step, feature, object, benefit,
advantage, or equivalent to the public, regardless of whether it is
or is not recited in the claims.
[0144] It will be understood that the terms and expressions used
herein have the ordinary meaning as is accorded to such terms and
expressions with respect to their corresponding respective areas of
inquiry and study except where specific meanings have otherwise
been set forth herein. Relational terms such as first and second
and the like may be used solely to distinguish one entity or action
from another without necessarily requiring or implying any actual
such relationship or order between such entities or actions. The
terms "comprises," "comprising," or any other variation thereof,
are intended to cover a non-exclusive inclusion, such that a
process, method, article, or apparatus that comprises a list of
elements does not include only those elements but may include other
elements not expressly listed or inherent to such process, method,
article, or apparatus. An element preceded by "a" or "an" does not,
without further constraints, preclude the existence of additional
identical elements in the process, method, article, or apparatus
that comprises the element.
[0145] The Abstract of the Disclosure is provided to allow the
reader to quickly ascertain the nature of the technical disclosure.
It is submitted with the understanding that it will not be used to
interpret or limit the scope or meaning of the claims. In addition,
in the foregoing Detailed Description, it can be seen that various
features are grouped together in various embodiments for the
purpose of streamlining the disclosure. This method of disclosure
is not to be interpreted as reflecting an intention that the
claimed embodiments require more features than are expressly
recited in each claim. Rather, as the following claims reflect,
inventive subject matter lies in less than all features of a single
disclosed embodiment. Thus, the following claims are hereby
incorporated into the Detailed Description, with each claim
standing on its own as a separately claimed subject matter.
* * * * *