U.S. patent application number 14/605481 was filed with the patent office on 2016-07-28 for method and apparatus for in-channel interference cancellation.
The applicant listed for this patent is MOTOROLA SOLUTIONS, INC. Invention is credited to NEIYER S. CORREAL, JOSEPH P. HECK, SPYROS KYPEROUNTAS, QICAI SHI, ROBERT E. STENGEL.
Application Number | 20160218754 14/605481 |
Document ID | / |
Family ID | 56235039 |
Filed Date | 2016-07-28 |
United States Patent
Application |
20160218754 |
Kind Code |
A1 |
SHI; QICAI ; et al. |
July 28, 2016 |
METHOD AND APPARATUS FOR IN-CHANNEL INTERFERENCE CANCELLATION
Abstract
A communication device includes a receiver that is capable of
canceling in-channel interference. The receiver includes an antenna
for receiving a wireless signal comprising in-channel components
and an out-of-channel component, wherein the in-channel components
comprise a desired component and an in-channel interference
component. A first filter of the receiver filters the wireless
signal by blocking at least a portion of the out-of-channel
component to produce a first signal comprising the in-channel
components, and at least a second filter of the receiver filters
the wireless signal by blocking at least a portion of the
in-channel components to produce a second signal comprising the
out-of-channel component. An in-channel interference estimator of
the receiver generates an in-channel interference estimation signal
based on the second signal. And a combiner of the filter combines
the first signal and the second signal to at least partially cancel
the in-channel interference component of the first signal.
Inventors: |
SHI; QICAI; (CORAL SPRINGS,
FL) ; CORREAL; NEIYER S.; (COOPER CITY, FL) ;
HECK; JOSEPH P.; (FT LAUDERDALE, FL) ; KYPEROUNTAS;
SPYROS; (WESTON, FL) ; STENGEL; ROBERT E.;
(POMPANO BEACH, FL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MOTOROLA SOLUTIONS, INC |
Schaumburg |
IL |
US |
|
|
Family ID: |
56235039 |
Appl. No.: |
14/605481 |
Filed: |
January 26, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04J 11/0066 20130101;
H04B 1/1036 20130101; H04L 25/03821 20130101 |
International
Class: |
H04B 1/04 20060101
H04B001/04 |
Claims
1. A method for interference cancellation in a wireless
communication system, the method comprising the steps of: receiving
first, second, and third non-overlapping portions of spectrum;
using the first and the second non-overlapping portions of spectrum
to estimate power amplifier coefficients used to generate the first
and the second portions of spectrum; using the power amplifier
coefficients to predict interference within the third portion of
spectrum; using the predicted interference to cancel interference
within the third portion of spectrum; and wherein the step of using
the first and the second non-overlapping portions of spectrum to
estimate power amplifier coefficients the step of using a minimum
mean squared error (MMSE) criterion to find coefficients of a
3.sup.rd term, 5.sup.th term and 7.sup.th term by finding vector
.alpha. that minimizes: argmin .alpha. .fwdarw. S OOBE - .alpha.
.fwdarw. * S .fwdarw. ' ##EQU00004## where {right arrow over
(.alpha.)}=[.alpha..sub.31.alpha..sub.32 . . .
.alpha..sub.3L.alpha..sub.51.alpha..sub.52 . . .
.alpha..sub.5L.alpha..sub.71.alpha..sub.72 . . .
.alpha..sub.7L].
2. The method of claim 1 wherein the first, second, and third
non-overlapping portions of spectrum comprise a wideband
transmission (S.sub.LTE), an interference (S.sub.OOBE), and a
narrowband channel (NB PS), respectively.
3. (canceled)
4. The method of claim 1 further comprising the steps of:
calculating S LTE = S LTE / mean ( S LTE 2 ) , S 3 rd = ( S LTE ) 2
* S LTE , S 5 th = ( S LTE ) 4 * S LTE , S 7 th = ( S _ LTE ) 6 * S
LTE , S ' ? = Bandpass_Filter ? , ? = Bandpass_Filter ? , S 7 th '
= Bandpass_Filter ( S 7 th ) , and wherein ##EQU00005## S '
.fwdarw. = [ S 3 rd ' ( n ) S 3 rd ' ( n - 1 ) S 3 rd ' ( n - L + 1
) S 5 th ' ( n ) S 5 th ' ( n - 1 ) S 5 th ' ( n - L + 1 ) S 7 th '
( n ) S 7 th ' ( n - 1 ) S 7 th ' ( n - L + 1 ) ] ##EQU00005.2## ?
indicates text missing or illegible when filed ##EQU00005.3##
5. (canceled)
6. (canceled)
7. An apparatus comprising: at least one antenna receiving first,
second, and third non-overlapping portions of spectrum; a first
estimator using the first and the second non-overlapping portions
of spectrum to estimate power amplifier coefficients used to
generate the first and the second portions of spectrum; a second
estimator using the power amplifier coefficients to predict
interference within the third portion of spectrum; interference
suppression circuitry using the predicted interference to cancel
interference within the third portion of spectrum; wherein the
first, second, and third non-overlapping portions of spectrum
comprise a wideband transmission (S.sub.LTE), an interference
(S.sub.OOBE) 402, and a narrowband channel (NB PS), respectively;
and wherein, the power amplifier coefficients comprise coefficients
of a 3.sup.rd term, 5.sup.th term and 7.sup.th term of a vector
.alpha. that minimizes argmin .alpha. .fwdarw. S OOBE - .alpha.
.fwdarw. * S ' .fwdarw. ##EQU00006##
8. (canceled)
9. (canceled)
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to wireless
communication systems, and in particular to in-channel interference
cancellation in a wireless communication system.
BACKGROUND OF THE INVENTION
[0002] When a broadband radio transmitter, such as a 700 MHz
(Megahertz) Broadband Long Term Evolution (LTE) transmitter, is
operating in the vicinity of a narrowband radio receiver, such as a
Public Safety (PS) narrowband receiver, out-of-band emissions
(OoBE) of the broadband transmitter may cause considerable
interference to the narrowband PS receiver. The broadband
transmitter's OoBE will sum with the noise of the receiver,
resulting in a decrease in signal to interference-plus-noise ratio
(SINR) at the narrowband PS receiver and thereby desensitize the
receiver.
[0003] For example, FIG. 1 is an exemplary spectral graph 100
depicting a broadband signal 102 whose frequency band 108 is in
close proximity to the frequency band 112 of a narrowband signal
106. Despite the inclusion of a guard band 110 as a buffer between
the broadband signal and adjacent signals, such as narrowband
signal 106, an OoBE 104 of broadband signal 102 still spills into
the bandwidth of narrowband signal 106, resulting in receiver
desensitization, that is, reduced Signal-to-Noise Ratio (SNR) 114
at a narrowband receiver.
[0004] For example, such receiver desensitization is known to occur
in cases such as the C band, where the close proximity of the C
block uplink (transmit) band to the Public Safety Narrowband
(receive) band causes desensitization of a narrowband receiver when
in close proximity to a C band uplink transmitter. More
specifically, in the 700-800 MHz band, the 1 MHz guard band
separating the C band uplink (776-787 MHz) from the adjacent Public
Safety Narrowband (PSNB) (769-775 MHz) may fail to adequately
protect PSNB transmissions from interference from a nearby C band
transmitter. While interference in the PSNB by the C band uplink
transmissions may be mitigated by improved filtering at a C band
transmitter, improving such filtering can be difficult and
expensive to implement and retrofitting transmitters that belong to
non-public safety (third) parties or the public poses significant
challenges. Therefore, a need exists for a method and apparatus for
channel interference cancellation in a wireless communication
system in order to mitigate the above-described interference.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] FIG. 1 is an exemplary spectral graph depicting a broadband
signal whose frequency band is in close proximity to a frequency
band of a narrowband signal.
[0006] FIG. 2 is a block diagram of a wireless communication system
in accordance with an embodiment of the present invention.
[0007] FIG. 3 is a block diagram of a wireless receiving
communication device of FIG. 2 in accordance with various
embodiments of the present invention.
[0008] FIG. 4 is an exemplary spectral graph depicting a broadband
signal whose frequency band is in close proximity to a frequency
band of a narrowband signal.
[0009] FIG. 5 depicts an architecture of the receiver of the
wireless receiving communication device of FIG. 2 in accordance
with another embodiment of the present invention.
[0010] FIG. 6 is a logic flow diagram illustrating a method by
which the wireless receiving communication device of FIG. 2 cancels
in-channel interference in accordance with an embodiment of the
present invention.
[0011] Skilled artisans will appreciate that elements in the
figures are illustrated for simplicity and clarity and have not
necessarily been drawn to scale. For example, the dimensions and/or
relative positioning of some of the elements in the figures may be
exaggerated relative to other elements to help to improve
understanding of various embodiments of the present invention.
Also, common but well-understood elements that are useful or
necessary in a commercially feasible embodiment are often not
depicted in order to facilitate a less obstructed view of these
various embodiments of the present invention. It will further be
appreciated that certain actions and/or steps may be described or
depicted in a particular order of occurrence while those skilled in
the art will understand that such specificity with respect to
sequence is not actually required. Those skilled in the art will
further recognize that references to specific implementation
embodiments such as "circuitry" may equally be accomplished via
replacement with software instruction executions either on general
purpose computing apparatus (e.g., CPU) or specialized processing
apparatus (e.g., DSP). It will also be understood that the terms
and expressions used herein have the ordinary technical meaning as
is accorded to such terms and expressions by persons skilled in the
technical field as set forth above except where different specific
meanings have otherwise been set forth herein.
DESCRIPTION OF A PREFERRED EMBODIMENT
[0012] To address the need for a mitigation of in-channel
interference, a communication device is provided that includes a
receiver that is capable of canceling in-channel interference. The
receiver includes an antenna for receiving a wireless signal
comprising in-channel components and an out-of-channel component,
wherein the in-channel components comprise a desired component and
an in-channel interference component. A first filter of the
receiver filters the wireless signal by blocking at least a portion
of the out-of-channel component to produce a first signal
comprising the in-channel components, and at least a second filter
of the receiver filters the wireless signal by blocking at least a
portion of the in-channel components to produce a second signal
comprising the out-of-channel component. An in-channel interference
estimator of the receiver generates an in-channel interference
estimation signal based on the second signal. And a combiner
combines the first signal and the second signal to at least
partially cancel the in-channel interference component of the first
signal.
[0013] The present invention may be more fully described with
reference to the figures. Turning now to the drawings, wherein like
numerals designate like components, FIG. 2 is a block diagram of a
wireless communication system 200 in accordance with an embodiment
of the present invention. Communication system 200 includes
multiple wireless transmitting communication devices 202, 204 (two
shown) and a wireless receiving communication device 206 that is
located in a coverage area of each of the transmitting
communication devices. For example, each of transmitting
communication devices 202, 204 may be a radio access network (RAN)
access node such as a base station, a Node B, a Public Safety Base
Station or an access point, or a User Equipment (UE) terminal, and
receiving communication device 206 may be a user communication
device such as a cellular telephone, a radiotelephone, a
smartphone, or a personal digital assistant, laptop computer,
tablet computer, or personal computer with wireless communication
capabilities. However, in various embodiments of the present
invention, one or more of transmitting communication devices 202
and 204 may be a user communication device and/or receiving
communication device 206 may be a RAN access node. Each of
transmitting communication device 202 and 204 transmits over a
respective air interface 212, 214 that includes a forward link (not
shown) and a reverse link (not shown).
[0014] FIG. 3 is a block diagram of receiving communication device
206 in accordance with various embodiments of the present
invention. Receiving communication device 206 includes a processor
302, such as one or more microprocessors, microcontrollers, digital
signal processors (DSPs), combinations thereof or such other
devices known to those having ordinary skill in the art. Processor
302 is coupled to an at least one memory device 304, such as random
access memory (RAM), dynamic random access memory (DRAM), and/or
read only memory (ROM) or equivalents thereof, that maintains data
and programs that may be executed by the processor and that allow
the communication device to perform all functions necessary to
operate in a wireless communication system. Communication device
206 further includes a receiver 306, and optionally may include a
transmitter 308, that each are operationally coupled to processor
302 and to an antenna 300 and that provide for wirelessly receiving
and transmitting messages by the communication device.
[0015] Communication system 200 may be any type of wireless
communication wherein different devices transmit signals at
different frequencies, even if some transmitting devices share a
frequency bandwidth. For example, communication system 200 may
comprise one or more of a Frequency Division Multiple Access (FDMA)
communication network, a Global System for Mobile communications
(GSM) communication network, a Code Division Multiple Access (CDMA)
communication network, any type of communication network that
employs an Orthogonal Frequency Division Multiplexing (OFDM)
modulation scheme, such as a 3GPP (Third Generation Partnership
Project) E-UTRA (Evolutionary UMTS Terrestrial Radio Access)
communication network, a 3GPP2 (Third Generation Partnership
Project 2) Evolution communication network, for example, an Ultra
Mobile Broadband (UMB) communication network, a Worldwide
Interoperability for Microwave Access (WiMAX) communication network
that operates in accordance with the IEEE (Institute of Electrical
and Electronics Engineers) 802.16 standards, a Wireless Local Area
Network (WLAN) communication system as described by the IEEE 802.xx
standards, for example, the 802.11a/HiperLAN2, 802.11g, or 802.20
standards, or any of multiple proposed ultrawideband (UWB)
communication networks.
[0016] The multiple transmitting communication devices 202, 204 may
be operated by a same network operator and may be part of a same
communication network, or one or more of the multiple transmitting
communication devices 202, 204 may be operated by a different
network operator and be part of a different communication network
than another transmitting communication device of the multiple
transmitting communication devices. For example, a first
transmitting communication device 202 of the multiple transmitting
communication devices 202, 204 may comprise a broadband
transmitter, such as a 700 MHz (Megahertz) Broadband Long Term
Evolution (LTE) transmitter, transmitting in the C band (776-787
MHz), while a second transmitting communication device 204 of the
multiple transmitting communication devices 202, 204 may comprise a
narrowband transmitter, such as a Public Safety (PS) narrowband
transmitter, transmitting in the adjacent Public Safety Narrowband
(PSNB) (769-775 MHz) and separated from the C band by a 1 MHz guard
band.
[0017] When coverage areas 212 and 214 of transmitting
communication devices 202 and 204 overlap, it is possible that a
communication device, such as receiving communication device 206,
located in the area of overlap and served by one of the multiple
transmitting communication devices 202, 204, for example, by a
first transmitting communication device 202, may receive
transmissions from both serving transmitting communication device
202 and a second transmitting communication device 204. In such an
instance, out-of-channel emissions, or out-of-band emissions
(OoBE), related to transmissions by second transmitting
communication device 204 may produce in-channel interference with
respect to desired signals received from the first transmitting
communication device 202. Such in-channel interference can
desensitize receiver 306 of receiving communication device 206 and
prevent the receiving communication device from correctly
demodulating and decoding desired signals from first transmitting
communication device 202. Therefore, communication system 200
minimizes the effect of such in-channel interference by providing
for cancellation, by a receiving communication device, of
in-channel interference generated by out-of-channel transmissions,
thereby facilitating an ability of the receiving communication
device to correctly demodulate and decode in-channel signals in the
presence of such interference.
[0018] FIG. 4 is an exemplary spectral graph depicting a broadband
signal whose frequency band is in close proximity to a frequency
band of a narrowband signal. In order to help describe the
embodiment shown in FIG. 5, FIG. 4 shows three particular bands
utilized by the receiver 306 when performing interference
cancellation. In particular, active wideband transmission
(S.sub.LTE) 401, interference (S.sub.OoBE) 402, and a narrowband
channel (NB PS) 403 are illustrated. As described, wideband
transmission 401 is preferably generated by transmitter such as a
700 MHz (Megahertz) Broadband Long Term Evolution (LTE)
transmitter. This transmission causes interference, for example,
interference 402 that lie outside transmission 401. It should be
noted that interference 402 has a portion that exist outside
narrowband channel 403, and a portion that interferes with
narrowband channel 403. In this particular example, interference
portion 402 lies outside both signals 401 and 403. Finally,
narrowband channel 403 is preferably a narrowband transmission
generated by a transmitter, such as a Public Safety (PS) narrowband
transmitter.
[0019] It should be noted that interference portion 402 may
comprise many different types of interference. Such interference
includes side lobes created by a modulation scheme used by a
wideband transmitter as well as of band emissions due to the
non-linear effects of a wideband power amplifier (PA). It is the
latter interference (which may be thought of as "spectral
re-growth" due to non linear PA effects) that is cancelled by the
receiver of FIG. 5.
[0020] FIG. 5 depicts receiver 306 in more detail. As shown
receiver 306 comprises antenna 501, filters 502-504, Power
Amplifier (PA) coefficient estimator 505, OOBE in NBPS band
estimator 506, Interference suppression circuitry 507, baseband
filter 508, and narrowband receiver 509. It should be noted that
while estimators 505 and 506, and suppression circuitry 507 are
shown as stand-alone components, these function of these components
may take place using microprocessor 302. During operation, antenna
501 receives at least the three frequency bands 401, 402, and 403
as a received RF signal. Antenna 501 routes a received RF signal to
each of the multiple filters for example, by use of a signal
splitter (not shown) or by use of one or more signal sampling
devices such as a directional couplers (not shown). Filter 502
filters the received signal to produce S.sub.LTE 401 without
signals 402 or 403. Similarly, filter 503 filters the received
signal to produce S.sub.OOBE 402 without signals 401 or 403.
Finally, filter 504 filters the received signal to produce NB PS
403 without signals 401 or 402.
[0021] Using the output of filter 502 (S.sub.LTE) and the reference
which is the output of filter 503 (S.sub.OOBE) estimator 505
estimates the coefficients of the assumed PA model. Then the output
of filter 502 (S.sub.LTE) is used as an input to the PA model with
the estimated coefficients to generate an estimate of the
interference in the PS Band. This is done in estimator 506. This is
described in more detail below.
[0022] During operation, S.sub.LTE 401 enters PA coefficient
estimator 505 where a power amplifier model coefficients are
estimated. As one of ordinary skill in the art will recognize,
power amplifier model coefficients are the coefficients from a
memory polynomial model of the Power Amplifier. With the memory
based baseband polynomial model, the PA output is represented
as
y n = m = 0 L s n - m k = 1 P .alpha. km s n - m k - 1
##EQU00001##
[0023] and the .alpha..sub.km are the memory polynomial model
coefficients that provide the best description of the power
amplifier, L is the maximum delay in samples and P is the order of
polynomial considered. As one of ordinary skill in the art will
recognize, other PA models could also be used, with interference
being cancelled as described below by estimating model
coefficients.
Estimator 505 calculates:
S.sub.LTE=S.sub.LTE/ {square root over (mean(S.sub.LTE.sup.2))}
S.sub.3rd=(|S.sub.LTE|).sup.2*S.sub.LTE
S.sub.5th=(|S.sub.LTE|).sup.4*S.sub.LTE
S.sub.7th=(|S.sub.LTE|).sup.6*S.sub.LTE.
[0024] Estimator 505 then band-pass filters the above to
produce:
S'.sub.3rd=Bandpass_Filter(S.sub.3rd)
S'.sub.5th=Bandpass_Filter(S.sub.5th)
S'.sub.7th=Bandpass_Filter(S.sub.7th)
[0025] Estimator 505 then uses a minimum mean squared error (MMSE)
criterion to find the coefficients of the 3.sup.rd term, 5.sup.th
term and 7.sup.th term by finding the vector .alpha. that
minimizes:
argmin .alpha. .fwdarw. S OOBE - .alpha. .fwdarw. S ' .fwdarw.
##EQU00002## Where ##EQU00002.2## .alpha. .fwdarw. - [ .alpha. 31
.alpha. 32 .alpha. 3 L .alpha. 5 1 .alpha. 52 .alpha. 5 L .alpha.
71 .alpha. 72 .alpha. 7 L ] ##EQU00002.3## and ##EQU00002.4## S '
.fwdarw. = [ S 3 rd ' ( n ) S 3 rd ' ( n - 1 ) S 3 rd ' ( n - L + 1
) S 5 th ' ( n ) S 5 th ' ( n - 1 ) S 5 th ' ( n - L + 1 ) S 7 th '
( n ) S 7 th ' ( n - 1 ) S 7 th ' ( n - L + 1 ) ]
##EQU00002.5##
[0026] Thus, the vector of coefficients {right arrow over
(.alpha.)} is found to minimize an error between the actual
interference signal and the estimate of the interference signal.
The estimate is a function of the {right arrow over (.alpha.)}
coefficients.
[0027] It should be noted that L is an integer, L>=1. For
L>1, for when the 3rd, 5th, 7th correction terms include memory
effects. Thus each correction term to be estimated, is now also
dependent on past samples of the signal and not only current ones.
For example if L=2 each correction term (3rd, 5th, 7th) will now
have 2 coefficients, one for the current sample and one for the
sample that came before.
[0028] The power amplifier coefficients {right arrow over
(.alpha.)}=[.alpha..sub.31.alpha..sub.32 . . .
.alpha..sub.3L.alpha..sub.51.alpha..sub.52 . . .
.alpha..sub.5L.alpha..sub.71.alpha..sub.72 . . . .alpha..sub.7L]
are utilized along with S.sub.OOBE 402 to estimate the OOBE that
exists within NB PS 403 (estimated interference). This is
accomplished by circuitry 506 linear combining the 3.sup.rd term,
5.sup.th term and 7.sup.th term to get the estimated OOBE signal
within band 403. More particularly,
S ^ OOBE - .alpha. .fwdarw. S .fwdarw. ##EQU00003## Where
##EQU00003.2## S .fwdarw. = [ S 3 rd ( n ) S 3 rd ( n - 1 ) S 3 rd
( n - L + 1 ) S 5 th ( n ) S 5 th ( n - 1 ) S 5 th ( n - L + 1 ) S
7 th ( n ) S 7 th ( n - 1 ) S 7 th ( n - L + 1 ) ]
##EQU00003.3##
[0029] The estimated interference is passed to interference
suppression circuitry 507 where it is subtracted from NB PS 403 to
produce a clean NB PS. More particularly, circuitry 507 produces
{tilde over (S)}=S-S.sub.OOBE, and passes this to filter 508 and
ultimately to receiver 509.
[0030] FIG. 6 is a logic flow diagram illustrating a method by
which the wireless receiving communication device of FIG. 2 cancels
in-channel interference in accordance with an embodiment of the
present invention. The logic flow begins at step 601 where antenna
501 receives a radio-frequency transmission comprising a first,
second, and third non-overlapping portions of spectrum. More
particularly, antenna 501 receives S.sub.LTE+S.sub.OOBE+NB PS.
Filter 502 filters the received signal to produce S.sub.LTE 401
without signals 402 or 403 (step 603). Similarly, filter 503
filters the received signal to produce S.sub.OOBE 402 without
signals 401 or 403 (step 605). Filter 504 filters the received
signal to produce NB PS 403 without signals 401 or 402 (step 607).
It should be noted that NB PS 403 does contain interference caused
from a wideband transmitter (as discussed above). At step 609
S.sub.LTE 401 and S.sub.OOBE enters PA coefficient estimator 505
where power amplifier coefficients are estimated. More
particularly, the first and the second non-overlapping portions of
spectrum are used to estimate power amplifier coefficients used to
generate the first and the second portions of spectrum.
[0031] The estimated power amplifier coefficients are utilized
along with S.sub.OOBE 402 at step 611 to estimate the OOBE that
exists within NB PS 403 (estimated interference). In other words,
the estimated power amplifier coefficients are used to predict
interference within the third portion of spectrum. Finally, at step
613 the estimated interference is passed to interference
suppression circuitry 507 where it is subtracted from NB PS 403 to
produce a clean NB PS that is passed to filter 508 and ultimately
to receiver 509. As is evident the estimated/predicted interference
is used to cancel interference within the third portion of
spectrum.
[0032] The benefits, advantages, solutions to problems, and any
element(s) that may cause any benefit, advantage, or solution to
occur or become more pronounced are not to be construed as a
critical, required, or essential features or elements of any or all
the claims. The invention is defined solely by the appended claims
including any amendments made during the pendency of this
application and all equivalents of those claims as issued.
[0033] Moreover in this document, relational terms such as first
and second, top and bottom, and the like may be used solely to
distinguish one entity or action from another entity or action
without necessarily requiring or implying any actual such
relationship or order between such entities or actions. The terms
"comprises," "comprising," "has", "having," "includes",
"including," "contains", "containing" or any other variation
thereof, are intended to cover a non-exclusive inclusion, such that
a process, method, article, or apparatus that comprises, has,
includes, contains 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
proceeded by "comprises . . . a", "has . . . a", "includes . . .
a", "contains . . . a" does not, without more constraints, preclude
the existence of additional identical elements in the process,
method, article, or apparatus that comprises, has, includes,
contains the element. The terms "a" and "an" are defined as one or
more unless explicitly stated otherwise herein. The terms
"substantially," "essentially," "approximately," "about," or any
other version thereof, are defined as being close to as understood
by one of ordinary skill in the art, and in one non-limiting
embodiment the term is defined to be within 10%, in another
embodiment within 5%, in another embodiment within 1% and in
another embodiment within 0.5%. The term "coupled" as used herein
is defined as connected, although not necessarily directly and not
necessarily mechanically. A device or structure that is
"configured" in a certain way is configured in at least that way,
but may also be configured in ways that are not listed.
[0034] 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.
* * * * *