U.S. patent application number 14/094644 was filed with the patent office on 2014-03-27 for system and method for distinguishing between antennas in hybrid mimo rdn systems.
This patent application is currently assigned to Magnolia Broadband Inc.. The applicant listed for this patent is Magnolia Broadband Inc.. Invention is credited to Eduardo Abreu, Haim Harel, Kenneth KLUDT.
Application Number | 20140086354 14/094644 |
Document ID | / |
Family ID | 49640798 |
Filed Date | 2014-03-27 |
United States Patent
Application |
20140086354 |
Kind Code |
A1 |
KLUDT; Kenneth ; et
al. |
March 27, 2014 |
SYSTEM AND METHOD FOR DISTINGUISHING BETWEEN ANTENNAS IN HYBRID
MIMO RDN SYSTEMS
Abstract
A system for distinguishing between any one of a plurality of
antennas in a multiple-input-multiple-output (MIMO) system having
an augmented number of antennas is provided herein. The system
includes a MIMO receiving system having N branches and configured
to operate in accordance with a channel estimation MIMO receiving
scheme; a radio distribution network (RDN) connected to the MIMO
receiving system, the RDN comprising at least one beamformer, being
fed by two or more antennas, so that a total number of antennas in
the system is M, wherein M is greater than N, wherein each one of
the beamformers include a combiner configured to combine signals
coming from the antennas into a single signal; and at least one
antenna distinguishing circuitry, each associated with a respective
beamformer, wherein the antenna distinguishing circuitry is
configured to distinguish between the signals coming from the
antennas which feed the respective beamformer.
Inventors: |
KLUDT; Kenneth; (San Jose,
CA) ; Harel; Haim; (New York, NY) ; Abreu;
Eduardo; (Allentown, PA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Magnolia Broadband Inc. |
Englewood |
NJ |
US |
|
|
Assignee: |
Magnolia Broadband Inc.
Englewood
NJ
|
Family ID: |
49640798 |
Appl. No.: |
14/094644 |
Filed: |
December 2, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13762191 |
Feb 7, 2013 |
8599955 |
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14094644 |
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13630146 |
Sep 28, 2012 |
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13762191 |
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61652743 |
May 29, 2012 |
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61657999 |
Jun 11, 2012 |
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61665592 |
Jun 28, 2012 |
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61658015 |
Jun 11, 2012 |
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61658010 |
Jun 11, 2012 |
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61658012 |
Jun 11, 2012 |
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61658006 |
Jun 11, 2012 |
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61665590 |
Jun 28, 2012 |
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61665636 |
Jun 28, 2012 |
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Current U.S.
Class: |
375/267 |
Current CPC
Class: |
H04B 7/086 20130101;
H04B 7/0413 20130101; H04B 7/088 20130101; H04B 7/0802
20130101 |
Class at
Publication: |
375/267 |
International
Class: |
H04B 7/04 20060101
H04B007/04 |
Claims
1. A system comprising: a multiple-input-multiple-output (MIMO)
receiving system having N branches and configured to operate in
accordance with a channel estimation MIMO receiving scheme; and a
radio distribution network (RDN) connected to the MIMO receiving
system, the RDN comprising at least one beamformer, being fed by
two or more antennas, so that a total number of antennas in the
system is M, wherein M is greater than N and wherein N is an
integer greater than 1, wherein at least one of the beamformers
includes antenna distinguishing circuitry, wherein the antenna
distinguishing circuitry is configured to isolate individual
contributions of the signals feeding the beamformer.
2. The system according to claim 1, further comprising an RF
control module configured to control the antenna distinguishing
circuitry in accordance with a corresponding antenna distinguishing
scheme.
3. The system according to claim 1, wherein the MIMO receiving
system is further configured to derive at least one of: phase and
amplitude of each one of the distinguished signals, wherein the
derived phase or amplitude is usable for applying appropriate
weights to the RDN.
4. The system according to claim 1, wherein the beamformer with the
antenna distinguishing circuitry comprises radio frequency (RF)
elements including at least one of: a phase shifter, a switch, a
terminator, and an amplifier.
5. The system according to claim 1, wherein the beamformer with the
antenna distinguishing circuitry comprises a combiner configured to
combine signals coming from a plurality of antennas associated with
the beamformer into a single signal, and wherein selectable bypass
for each antenna configured to bypass the combiner in the
beamformer and convey the signal from the antenna to an output
selector, and wherein the output selector is configured to deliver
to the MIMO receiving system the signal from only one antenna at a
time.
6. The system according to claim 5, further comprising a
calibration element for each one of the selectable bypass units,
wherein the calibration element is configured to identify and take
into account phase and amplitude difference between the combiner
and the selectable bypass unit.
7. The system according to claim 5, wherein the beamformer with
antenna distinguishing circuitry is configured to selectively
disconnect and terminate all but one of the antennas so that only
one signal coming from the antennas is conveyed to the combiner
output, at a time.
8. The system according to claim 1, wherein the beamformer with
antenna distinguishing circuitry comprises a phase shifter for each
antenna, wherein the phase shifters are configured to change the
phase of only one signal coming from the antennas at a time, and
wherein the MIMO receiving system is configured to derive phase
and/or amplitude of the signal coming from the antenna with the
shifted phase by comparing the combined signals at two different
phases.
9. The system according to claim 1, wherein the beamformer with the
antenna distinguishing circuitry comprises an amplifier for each
antenna, wherein the amplifiers are configured to change the gain
of only one signal coming from the antenna at a time, and wherein
the MIMO receiving system is configured to derive phase and/or
amplitude of the signal coming from the amplified antenna by
comparing the combined signals at two different amplifications of
the signal.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation application of U.S.
patent application Ser. No. 13/762,191 filed on Feb. 7, 2013, which
is a continuation-in-part application of U.S. patent application
Ser. No. 13/630,146 filed on Sep. 28, 2012, which claims benefit
from US provisional patent applications: 61/652,743 filed on May
29, 2012; 61/657,999 filed on Jun. 11, 2012; and 61/665,592 filed
on Jun. 28, 2012; U.S. patent application Ser. No. 13/762,191 also
claims benefit from US provisional patent applications: 61/658,015
filed on Jun. 11, 2012; 61/658,010 filed on Jun. 11, 2012;
61/658,012 filed on Jun. 11, 2012; 61/658,006 filed on Jun. 11,
2012; 61/665,590 filed on Jun. 28, 2012; and 61/665,636 filed on
Jun. 28, 2012, all of the above applications are incorporated by
reference herein in their entirety.
FIELD OF THE INVENTION
[0002] The present invention relates generally to the field of
radio frequency (RF) multiple-input-multiple-output (MIMO) systems
and in particular to systems and methods for enhanced performance
of RF MIMO systems using RF beamforming and/or digital signal
processing.
BACKGROUND OF THE INVENTION
[0003] Prior to setting forth a short discussion of the related
art, it may be helpful to set forth definitions of certain terms
that will be used hereinafter.
[0004] The term "MIMO" as used herein, is defined as the use of
multiple antennas at both the transmitter and receiver to improve
communication performance. MIMO offers significant increases in
data throughput and link range without additional bandwidth or
increased transmit power. It achieves this goal by spreading the
transmit power over the antennas to achieve spatial multiplexing
that improves the spectral efficiency (more bits per second per Hz
of bandwidth) or to achieve a diversity gain that improves the link
reliability (reduced fading), or increased antenna directivity.
[0005] The term "beamforming" sometimes referred to as "spatial
filtering" as used herein, is a signal processing technique used in
antenna arrays for directional signal transmission or reception.
This is achieved by combining elements in the array in such a way
that signals at particular angles experience constructive
interference while others experience destructive interference.
Beamforming can be used at both the transmitting and receiving ends
in order to achieve spatial selectivity.
[0006] The term "beamformer" as used herein refers to RF circuitry
that implements beamforming and usually includes a combiner and may
further include switches, controllable phase shifters, and in some
cases amplifiers.
[0007] The term "Receiving Radio Distribution Network" or "Rx RDN"
or simply "RDN" as used herein is defined as a group of beamformers
as set forth above.
[0008] In MIMO systems the channel is estimated by the receiver via
measurements done over known patterns (e.g. transmitted Pilots);
the channel estimation is used for received data decoding. While
channel estimation is continuously performed by the receiver, the
channel information corresponds to the combined channel and not to
the individual Rx antennas. When an Rx beamformer is used and needs
tuning for achieving desired weights, the channel estimation
measurements are re-used by the beamformer, registering phases,
amplitudes, SINRs of the various incoming signals from different
antennas. Since the signals of the various antennas are combined,
the assessment of each one's contribution is blurred by the others'
contribution; therefore a mechanism to isolate individual
contributions of each antenna is required. This mechanism has
various possible implementations and is labeled "Antenna
Distinguishing".
BRIEF SUMMARY OF EMBODIMENTS OF THE INVENTION
[0009] According to some embodiments of the present invention, a
system for distinguishing antennas in a
multiple-input-multiple-output (MIMO) system is provided herein.
The system may include a MIMO receiving system having N branches
and configured to operate in accordance with a channel estimation
MIMO receiving scheme; a radio distribution network (RDN) connected
to the MIMO receiving system, the RDN comprising at least one
beamformer, being fed by two or more antennas, so that a total
number of antennas in the system is M, wherein M is greater than N,
wherein each one of the beamformers has antenna distinguishing
circuitry capable of distinguishing between the signals coming from
the antennas which feed the respective beamformer, the beamformers
also including a combiner configured to combine signals coming from
the antennas which feed the respective beamformer into a single
signal.
[0010] According to some embodiments of the present invention, a
method of distinguishing antennas in a
multiple-input-multiple-output (MIMO) system is provided herein.
The method includes the following stages: receiving radio frequency
(RF) MIMO transmission via M antennas coupled to a MIMO receiving
system having N branches and configured to operate in accordance
with a channel estimation MIMO receiving scheme, wherein M is
greater than N; beamforming groups of two or more of the M antennas
into each one of the N channels by combining signals coming from
the antennas into a combined signal; and distinguishing between the
signals coming from the antennas in each one of the groups by
applying RF manipulation during the beamforming.
[0011] These additional, and/or other aspects and/or advantages of
the present invention are set forth in the detailed description
which follows.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] For a better understanding of the invention and in order to
show how it may be implemented, references are made, purely by way
of example, to the accompanying drawings in which like numerals
designate corresponding elements or sections. In the accompanying
drawings:
[0013] FIG. 1 is a high level block diagram illustrating a system
according to embodiments of the present invention;
[0014] FIG. 2 is a high level block diagram illustrating one aspect
of a system according to embodiments of the present invention;
[0015] FIG. 3 is a high level block diagram illustrating another
aspect of a system according to embodiments of the present
invention;
[0016] FIG. 4 is a high level block diagram illustrating yet
another aspect of a system according to embodiments of the present
invention;
[0017] FIG. 5 is a signal diagram illustrating an aspect of a
method according to some embodiments of the present invention;
[0018] FIG. 6 is a signal diagram illustrating another aspect of a
method according to some embodiments of the present invention;
[0019] FIG. 7 is a high level block diagram illustrating yet
another aspect of a system according to embodiments of the present
invention;
[0020] FIGS. 8A and 8B are signal diagrams illustrating yet another
aspect of a method according to some embodiments of the present
invention; and
[0021] FIG. 9 is a high level flowchart illustrating a method
according to some embodiments of the present invention.
[0022] The drawings together with the following detailed
description make the embodiments of the invention apparent to those
skilled in the art.
DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION
[0023] With specific reference now to the drawings in detail, it is
stressed that the particulars shown are for the purpose of example
and solely for discussing the preferred embodiments of the present
invention, and are presented in the cause of providing what is
believed to be the most useful and readily understood description
of the principles and conceptual aspects of the invention. In this
regard, no attempt is made to show structural details of the
invention in more detail than is necessary for a fundamental
understanding of the invention. The description taken with the
drawings makes apparent to those skilled in the art how the several
forms of the invention may be embodied in practice.
[0024] Before explaining the embodiments of the invention in
detail, it is to be understood that the invention is not limited in
its application to the details of construction and the arrangement
of the components set forth in the following descriptions or
illustrated in the drawings. The invention is applicable to other
embodiments and may be practiced or carried out in various ways.
Also, it is to be understood that the phraseology and terminology
employed herein is for the purpose of description and should not be
regarded as limiting.
[0025] FIG. 1 is a high level block diagram illustrating a system
according to embodiments of the present invention. System 100
includes a multiple-input-multiple-output (MIMO) receiving system
baseband module 120 having N branches and configured to operate, on
the baseband level, in accordance with a channel estimation MIMO
receiving scheme. System 100 further includes a radio distribution
network 110 (RDN) connected to baseband module 120 via radio
circuits 12-1 to 12-N. RDN 110 includes at least one beamformer
with antenna distinguishing circuitry such as 140-1, being fed by
two or more antennas such as 10-1 to 10-K.sub.1, so that a total
number of antennas in system 100 is M=K.sub.1+K.sub.2+ . . .
+K.sub.N, wherein M is greater than N. Additionally, each one of
the beamformers includes a combiner (as shown in FIGS. 2-4)
configured to combine signals coming from the antennas into a
single combined signal converted to baseband by radio module 12-1
to 12-N. Baseband module 120 further includes an RF control module
being configured to tune RDN 110, for example by adjusting phase
shifters located within beamformers 140-1 to 140-N.
[0026] As shown above, system 100 includes one beamformer with
antenna distinguishing circuitry for each group of antennas that is
being combined into a single radio circuit. In operation, the
beamformer is configured to distinguish between (e.g., to isolate
individual contributions of) the signals coming from the antennas
which feed the respective radio circuits. As will be explained
below, there are many embodiments that may be used in order to
implement the signal distinguishing operation which is crucial for
derivation of phase and/or amplitude of each signal. These
distinguishing schemes may further be controlled via control module
130. As will be described below the beamformer with antenna
distinguishing circuitry may include radio frequency (RF) elements
such as phase shifters, switches, terminators, and amplifiers.
[0027] FIG. 2 is a high level block diagram illustrating one aspect
of a system according to embodiments of the present invention.
System 200 is an exemplary non limiting embodiment of 5 antennas
20-1 to 20-5 wherein the beamformer includes a selectable bypass
22-1 to 22-5 for each antenna 20-1 to 20-5 configured to bypass
combiner 210 in the respective beamformer and convey the signal
from each one of antennas 20-1 to 20-5 to an output selector 220,
and wherein the output selector is configured to deliver to the
MIMO receiving system only the signal from one antenna at a
time.
[0028] In some embodiments, it would be advantageous to provide a
calibration element (not shown) for each one of the selectable
bypass units, wherein the calibration element is configured to
identify and take into account phase and amplitude difference
between the combiner and the selectable bypass unit. The
calibration element may be implemented by any combination of
attenuator/amplifier and a phase shifter that may manipulate the
phase, the amplitude or both of F signal. The calibration process
may be carried out at the factory and may be either on the RF level
or the baseband level or a combination thereof.
[0029] FIG. 3 is a high level block diagram illustrating another
aspect of a system according to embodiments of the present
invention. In exemplary system 300 the beamformer is configured to
selectively disconnect and terminate all but one of the antennas so
that only one signal coming from the antennas is conveyed to the
output of the combiner, at a time. The disconnecting may be
implemented, for example, by a set of switches 32-1 to 32-5 each
switching a terminator for antennas 30-1 to 30-5. Each time, a
different antenna signal is conveyed alone via combiner 310.
[0030] FIG. 4 is a high level block diagram illustrating yet
another aspect of a system according to embodiments of the present
invention. In this exemplary embodiment, in system 400, the
beamformer is configured to selectively shift the phase of one
antenna signal at a time and then resume original phase. The
combined signal is compared after the phase is shifted and
immediately after the phase has been restored so that phase and
amplitude of the shifted phase shifter for each antenna can be
derived. This can be implemented by controllable phase shifters
42-1 to 42-5 that are controlled by an RF control module 130 (shown
in FIG. 1) configured to shift the phase of only one signal coming
from the antennas 40-1 to 40-5 at a time, so that the MIMO
receiving system may derive phase and/or amplitude of the signal
coming from the antenna with the shifted phase by comparing the
combined signals at two different phases. It should be noted that
controllable phase shifters 42-1 to 42-5 may also be used, when not
used to assist in the antenna distinguishing operation, to tune the
antennas as a part of the process of applying weights to the RDN as
a part of the channel estimation MIMO receiving scheme.
[0031] FIG. 5 is a signal diagram illustrating an aspect of a
method according to some embodiments of the present invention. In
this example, the phase of antenna 502i is changed in going from
time instance n-1 to n and becomes 504i as seen in 502 and 504
respectively. When looking at the combined signal at the respective
times n-1 and n, it is apparent that combined signal 522 is longer
than combined signal 528. This way both phase and amplitude of 502i
may be derived by applying a differential approach.
[0032] FIG. 6 is a signal diagram illustrating another aspect of a
method according to some embodiments of the present invention. In
this example the signal's phase of 602i is not aligned with the
rest of the signals coming from the rest of the antennas in 602 and
so the combined signals 622 and 624 illustrate that the phase
.PHI..sub.1 is different from .PHI..sub.2 and so again, both phase
and amplitude of the single antenna may be derived by way of
comparison.
[0033] FIG. 7 is a high level block diagram illustrating yet
another aspect of a system according to embodiments of the present
invention. In this exemplary embodiment, in system 400, the
beamformer includes a controllable amplifier 74-1 to 74-5 that is
controlled by an RF control module 130 (shown in FIG. 1) for each
antenna. The amplifiers are configured to amplify only one signal
coming from the antenna at a time, and wherein the MIMO receiving
system is configured to derive phase and/or amplitude of the signal
coming from the amplified antenna by comparing the combined signals
at two different amplifications.
[0034] FIG. 8A shows a signal diagram illustrating yet another
aspect of a method according to some embodiments of the present
invention. In this example, a signal 802i is amplified at time n-1
and resumed at time n as shown in 802 and 812. The combined signal
shown in 806 and 816 shows that the difference between them is
apparent and both phase and amplitude of the amplified antenna can
be derived. FIG. 8B illustrates this embodiment for a case in which
signal 822i is not aligned with the rest of the signals. Another
embodiment may be by using controllable attenuators instead of
amplifiers and the effect of amplifying a single antenna (or its
signal) may be achieved by attenuating the gain of all antennas but
one, being the antenna that needs distinguishing at a specified
point of time. It should be understood that many more
implementations of antenna distinguishing may be used, some of
which may include any combination of phase shifters, amplifiers,
and attenuators.
[0035] Whenever the antenna distinguishing procedure is carried out
with all antennas of a beamformer connected to the combiner, such
as in the embodiments shown in FIGS. 4-8 above, a differential
approach is used to derive channel information for the individual
antennas. Let h.sub.i(n) be the external channel from the
transmitter antenna to receiver antenna i at time instant n,
a.sub.i(n) and .phi..sub.i(n) be respectively the amplitude and
phase of the internal path through the beamformer from receive
antenna i to the output of the combiner at time instant n, and e(n)
be the estimation measurement provided by the receiver baseband at
time instant n. It should be noted that the amplitudes and phases
of the internal paths through the beamformer are known quantities.
The estimation h.sub.i(n) of channel h.sub.i(n) is derived from two
separate baseband measurements, for example two consecutive
measurements, e(n-1) and e(n), and is defined as:
h ^ i ( n ) = e ( n - 1 ) - e ( n ) a i ( n - 1 ) j .PHI. i ( n - 1
) - a i ( n ) j.PHI. i ( n ) ##EQU00001##
[0036] It should be noted that the estimation is perceived to be
most efficient when
.phi..sub.i(n)=.phi..sub.i(n-1)+180.degree..
[0037] FIG. 9 is a high level flowchart illustrating a method 900
according to some embodiments of the present invention. Method 900
may include the following stage: receiving radio frequency (RF)
multiple-input-multiple-output (MIMO) signals via M antennas
coupled to a MIMO receiving system having N branches and configured
to operate in accordance with a channel estimation MIMO receiving
scheme, wherein M is greater than N 910; beamforming groups of two
or more of the M antennas into each one of the N channels by
combining signals coming from the antennas into a combined signal
920; and applying a distinguishing procedure to the signals coming
from the antennas in each one of the groups by applying RF
manipulation during the beamforming, wherein the distinguishing
procedure enable distinguishing between any one of the signals
coming from the antennas, within the combined signal 930.
[0038] According to some embodiments of the present invention, the
aforementioned antenna distinguishing may be carried out in
accordance with a corresponding antenna distinguishing scheme being
controlled at a baseband domain, namely, by a digital signal
processor (DSP) executing a dedicated software.
[0039] According to some embodiments of the present invention,
method 900 may further include an optional stage of deriving at
least one of: phase and amplitude of each one of the distinguished
signals; and tuning the beamformer accordingly.
[0040] According to some embodiments of the present invention, the
aforementioned antenna distinguishing procedure may include
selectively applying bypasses for each antenna for bypassing the
combining so as to deliver to the MIMO receiving system only the
signal from one antenna at a time. In other embodiments, the
aforementioned antenna distinguishing procedure is carried out by
selectively disconnecting and terminating all but one of the
antennas so that only one signal coming the antennas is conveyed to
the MIMO receiving system, at a time. In other embodiments, the
aforementioned antenna distinguishing procedure is carried out by
selectively changing the phase of only one signal coming from the
antennas at a time, and wherein the method further comprises
deriving phase and/or amplitude of the signal coming from the
antenna with the shifted phase by comparing the combined signals at
two different phases. In yet other embodiments, the aforementioned
antenna distinguishing procedure is carried out by changing the
gain of only one signal coming from the antenna at a time, and
wherein the method further comprises deriving phase and/or
amplitude of the signal coming from the amplified antenna by
comparing the combined signals at two different amplifications.
[0041] According to some embodiments of the present invention,
method 900 may further include an optional stage of identifying and
taking into account phase and amplitude difference between the
combining and the bypassing.
[0042] As will be appreciated by one skilled in the art, aspects of
the present invention may be embodied as a system, method or an
apparatus. Accordingly, aspects of the present invention may take
the form of an entirely hardware embodiment, an entirely software
embodiment (including firmware, resident software, micro-code,
etc.) or an embodiment combining software and hardware aspects that
may all generally be referred to herein as a "circuit," "module" or
"system."
[0043] The aforementioned flowchart and block diagrams illustrate
the architecture, functionality, and operation of possible
implementations of systems and methods according to various
embodiments of the present invention. In this regard, each block in
the flowchart or block diagrams may represent a module, segment, or
portion of code, which comprises one or more executable
instructions for implementing the specified logical function(s). It
should also be noted that, in some alternative implementations, the
functions noted in the block may occur out of the order noted in
the figures. For example, two blocks shown in succession may, in
fact, be executed substantially concurrently, or the blocks may
sometimes be executed in the reverse order, depending upon the
functionality involved. It will also be noted that each block of
the block diagrams and/or flowchart illustration, and combinations
of blocks in the block diagrams and/or flowchart illustration, can
be implemented by special purpose hardware-based systems that
perform the specified functions or acts, or combinations of special
purpose hardware and computer instructions.
[0044] In the above description, an embodiment is an example or
implementation of the inventions. The various appearances of "one
embodiment," "an embodiment" or "some embodiments" do not
necessarily all refer to the same embodiments.
[0045] Although various features of the invention may be described
in the context of a single embodiment, the features may also be
provided separately or in any suitable combination. Conversely,
although the invention may be described herein in the context of
separate embodiments for clarity, the invention may also be
implemented in a single embodiment.
[0046] Reference in the specification to "some embodiments", "an
embodiment", "one embodiment" or "other embodiments" means that a
particular feature, structure, or characteristic described in
connection with the embodiments is included in at least some
embodiments, but not necessarily all embodiments, of the
inventions. It will further be recognized that the aspects of the
invention described hereinabove may be combined or otherwise
coexist in embodiments of the invention.
[0047] It is to be understood that the phraseology and terminology
employed herein is not to be construed as limiting and are for
descriptive purpose only.
[0048] The principles and uses of the teachings of the present
invention may be better understood with reference to the
accompanying description, figures and examples.
[0049] It is to be understood that the details set forth herein do
not construe a limitation to an application of the invention.
[0050] Furthermore, it is to be understood that the invention can
be carried out or practiced in various ways and that the invention
can be implemented in embodiments other than the ones outlined in
the description above.
[0051] It is to be understood that the terms "including",
"comprising", "consisting" and grammatical variants thereof do not
preclude the addition of one or more components, features, steps,
or integers or groups thereof and that the terms are to be
construed as specifying components, features, steps or
integers.
[0052] If the specification or claims refer to "an additional"
element, that does not preclude there being more than one of the
additional element.
[0053] It is to be understood that where the claims or
specification refer to "a" or "an" element, such reference is not
be construed that there is only one of that element.
[0054] It is to be understood that where the specification states
that a component, feature, structure, or characteristic "may",
"might", "can" or "could" be included, that particular component,
feature, structure, or characteristic is not required to be
included.
[0055] Where applicable, although state diagrams, flow diagrams or
both may be used to describe embodiments, the invention is not
limited to those diagrams or to the corresponding descriptions. For
example, flow need not move through each illustrated box or state,
or in exactly the same order as illustrated and described.
[0056] The term "method" may refer to manners, means, techniques
and procedures for accomplishing a given task including, but not
limited to, those manners, means, techniques and procedures either
known to, or readily developed from known manners, means,
techniques and procedures by practitioners of the art to which the
invention belongs.
[0057] The descriptions, examples, methods and materials presented
in the claims and the specification are not to be construed as
limiting but rather as illustrative only.
[0058] Meanings of technical and scientific terms used herein are
to be commonly understood as by one of ordinary skill in the art to
which the invention belongs, unless otherwise defined.
[0059] The present invention may be implemented in the testing or
practice with methods and materials equivalent or similar to those
described herein.
[0060] While the invention has been described with respect to a
limited number of embodiments, these should not be construed as
limitations on the scope of the invention, but rather as
exemplifications of some of the preferred embodiments. Other
possible variations, modifications, and applications are also
within the scope of the invention. Accordingly, the scope of the
invention should not be limited by what has thus far been
described, but by the appended claims and their legal
equivalents.
* * * * *