Court Opinion

ID: 3150604
Source: CourtListenerOpinion
Date Created: 2015-10-29 16:01:20.049343+00
Date Added: 2024-06-11T15:11:35.367039
License: Public Domain

United States Court of Appeals
      for the Federal Circuit
                ______________________

                  ATLAS IP, LLC,
                  Plaintiff-Appellant

                           v.

   MEDTRONIC, INC., MEDTRONIC USA, INC.,
        MEDTRONIC MINIMED, INC.,
         Defendants-Cross-Appellants
           ______________________

                 2015-1071, 2015-1105
                ______________________

   Appeals from the United States District Court for the
Southern District of Florida in No. 1:13-cv-23309-CMA,
Judge Cecilia M. Altonaga.
                 ______________________

               Decided: October 29, 2015
                ______________________

    GEORGE C. SUMMERFIELD, JR., Stadheim & Grear,
Ltd., Chicago, IL, argued for plaintiff-appellant. Also
represented by ROLF STADHEIM, ROBERT M. SPALDING.

    JOHN C. O’QUINN, Kirkland & Ellis LLP, Washington,
DC, argued for defendants-cross-appellants. Also repre-
sented by WILLIAM H. BURGESS; JEANNE M. HEFFERNAN,
AKSHAY S. DEORAS, New York, NY; LUKE DAUCHOT, Los
Angeles, CA.
                ______________________
2                           ATLAS IP, LLC   v. MEDTRONIC, INC.

    Before MOORE, REYNA, and TARANTO, Circuit Judges.
TARANTO, Circuit Judge.
    Atlas IP, LLC owns U.S. Patent No. 5,371,734, which
describes and claims a protocol for controlling wireless
network communications between a hub and remotes. In
December 2013, Atlas sued Medtronic, Inc., Medtronic
USA, Inc., and Medtronic MiniMed, Inc. (collectively,
“Medtronic”), alleging that certain Medtronic medical
products for monitoring a patient’s condition infringed the
’734 patent. In a related case, the United States District
Court for the Southern District of Florida adopted claim
constructions that, by agreement, govern the present case.
Atlas IP, LLC v. St. Jude Medical, Inc., No. 14-21006-CIV,
2014 WL 3764129 (S.D. Fla. July 30, 2014). The district
court in this case then issued two summary-judgment
orders concerning claim 21, the only claim at issue here.
It granted summary judgment of non-infringement by
Medtronic, J.A. 2–6; and it granted summary judgment
rejecting anticipation and obviousness challenges to claim
21, Atlas IP, LLC v. Medtronic, Inc., No. 13-23309-CIV,
2014 WL 5305577 (S.D. Fla. Oct. 15, 2014). Atlas appeals
the non-infringement ruling, which we affirm. Medtronic
cross-appeals the validity ruling, which we reverse. We
remand for further proceedings on invalidity.
                      BACKGROUND
     The ’734 patent, entitled “Medium Access Control
Protocol for Wireless Network,” notes the existence of
prior-art techniques for communication between a hub
and multiple remotes in wireless network systems. But,
it says, those systems presented a problem. They con-
sumed large amounts of battery power, as the remotes
had to leave their receivers on at all times. ’734 patent,
col. 4, lines 56–65.
    The specification describes means of conserving bat-
tery power. According to the summary of the invention,
ATLAS IP, LLC   v. MEDTRONIC, INC.                              3

the hub establishes a communication cycle within which
there are intervals for the hub to communicate with the
remotes and separate intervals for remotes to communi-
cate with the hub. See id., col. 5, lines 44–47; id., col. 5,
lines 50–54. The hub also provides an opportunity for
new remotes to join the network and, in addition, com-
municates with other hubs to avoid interference. See id.,
col. 5, line 67, through col. 6, line 2; id., col. 6, lines 53–56.
In the detailed description of embodiments, the specifica-
tion at one point says that the communication cycle “is
repeated on a continuous basis as long as the hub is
active.” See id., col. 11, lines 41–42.
     The invention summary further states that the hub
communicates the information about the intervals within
a communication cycle to the remotes. See id., col. 5, lines
47–50. Based on that information, the remotes know
when to expect to receive frames from the hub and when
to transmit any frames they have to the hub. See id., col.
5, lines 50–54. A remote therefore can turn off its receiver
during periods in which it does not expect to receive
frames from the hub, and it can turn off its transmitter
during periods in which it will not be transmitting frames
to the hub. See id., col. 5, lines 54–62. In that way, the
hub and remotes can communicate but “conserve consid-
erable [battery] power.” Id., col. 5, lines 62–66.
     Figure 3 illustrates a communication cycle, with the
“outbound” portion containing intervals for the hub to
transmit and the “inbound” portion containing intervals
for transmission opportunities (TXOP) for the remotes:
4                            ATLAS IP, LLC   v. MEDTRONIC, INC.

    Claim 21, the only claim at issue in this case, states:
       21. A communicator for wirelessly transmitting
    frames to and receiving frames from a[t] least one
    additional communicator in accordance with a
    predetermined medium access control protocol,
    the communicators which transmit and receive
    the frames constituting a Group, each communi-
    cator including a transmitter and a receiver for
    transmitting and receiving the frames respective-
    ly, the medium access control protocol controlling
    each communicator of the Group to effect prede-
    termined functions comprising:
      [a] designating one of the communicators [o]f
        the Group as a hub and the remaining the
        [sic] communicators of the Group as remotes;
      [b] the hub establishing repeating communica-
        tion cycles, each of which has intervals during
        which the hub and the remotes transmit and
        receive frames;
ATLAS IP, LLC   v. MEDTRONIC, INC.                        5

      [c] the hub transmitting information to the re-
        motes to establish the communication cycle
        and a plurality of predeterminable intervals
        during each communication cycle, the inter-
        vals being ones when the hub is allowed to
        transmit frames to the remotes, when the re-
        motes are allowed to transmit frames to the
        hub, and when each remote is expected to re-
        ceive a frame from the hub;
      [d] the remotes powering off their transmitters
        during times other than those intervals when
        the remote is allowed to transmit frames to
        the hub, by using the information transmitted
        from the hub;
      [e] the remotes powering off their receivers dur-
        ing times other than those intervals when the
        remote is expected to receive a frame from the
        hub, by using the information transmitted
        from the hub;
      [f] the hub transmitting two frames containing
        information to establish the plurality of pre-
        determinable intervals during each communi-
        cation cycle, the second frame containing the
        information to established [sic] the plurality
        of predeterminable intervals occurring before
        the intervals in which the remotes are al-
        lowed to transmit frames to the hub.
Id., col. 50, line 39, through col. 51, line 9 (bracketed
letters added for convenience; emphases added to high-
light language central to the issues on appeal).
    In this case, Atlas alleged that certain of Medtronic’s
cardiac defibrillators and insulin pumps infringed several
claims of the ’734 patent because of how certain compo-
nents communicated with each other. Medtronic asserted
counterclaims requesting a declaratory judgment of
6                           ATLAS IP, LLC   v. MEDTRONIC, INC.

invalidity of all the claims of the ’734 patent under 35
U.S.C. §§ 102, 103(a), and 112.
    In Atlas v. St. Jude Medical, the district court con-
strued claim terms that appear in several claims, includ-
ing claim 21. It held that “the hub establishing repeating
communication cycles”—in clause [b] of claim 21—means
“the hub defining in advance the starting time and dura-
tion for each repeating communication cycle.” And it held
that “the hub transmitting information to the remotes to
establish the communication cycle and a plurality of
predeterminable intervals during each communication
cycle”—in clause [c] of claim 21—means “the hub trans-
mitting to the remotes information necessary to know in
advance the starting time and duration of the communi-
cation cycle and of each of two or more predeterminable
intervals during each communication cycle.” Atlas v. St.
Jude Medical, 2014 WL 3764129, at *5–8 (emphasis
added).
    Medtronic moved for summary judgment of non-
infringement of the asserted claims, and the district court
granted the motion except as to claim 21. The district
court then reconsidered its ruling as to claim 21 and
granted summary judgment of non-infringement of claim
21 as well. Only claim 21 is at issue on appeal.
    The district court’s ruling rested on the “in advance”
portion of the claim construction. The parties disputed
whether, under the “in advance” construction, the end-
point of a communication cycle must be communicated to
the remotes before the cycle begins, as Medtronic argued,
or merely before the remotes transmit to the hub, as Atlas
argued. The court concluded that the accused devices do
not infringe “under either party’s construction.” J.A. 6.
    Separately, Atlas sought summary judgment rejecting
Medtronic’s anticipation and obviousness challenges to
claim 21. (Medtronic cross-moved for summary judgment
of anticipation, but its cross-motion was dismissed as
ATLAS IP, LLC   v. MEDTRONIC, INC.                        7

untimely, and that dismissal is not challenged on appeal.)
The district court granted Atlas’s motion. Atlas v. Med-
tronic, 2014 WL 5305577. The court rested its holding on
a new claim construction of language in clause [b] of claim
21: “communication cycles, each of which has intervals
during which the hub and the remotes transmit and
receive frames.” The court held: “The plain meaning
necessitates the hub and the remotes transmit and re-
ceive frames during each communication cycle, not that
the hub and the remotes simply may do so during a
communication cycle.” Id. at *3 (emphasis in original).
    After the court’s two summary-judgment rulings as to
claim 21, Medtronic’s counterclaims for invalidity of the
rest of the ’734 patent’s claims remained pending. Atlas
and Medtronic submitted a joint motion to dismiss the
counterclaims without prejudice, which the court granted.
The district court then entered an amended final judg-
ment reflecting the dismissal.
    Atlas appeals the district court’s summary-judgment
order of non-infringement. Medtronic cross-appeals the
district court’s summary judgment of no anticipation or
obviousness.
                           DISCUSSION
    We first consider this court’s jurisdiction, as we are
obliged to do even though neither party disputes it.
Wawrzynski v. H.J. Heinz Co., 728 F.3d 1374, 1378 (Fed.
Cir. 2013). We have jurisdiction over an appeal from a
final decision of a district court. 28 U.S.C. § 1295(a)(1).
Here, the district court entered judgment on the merits
rejecting all of Atlas’s claims in its complaint and entered
judgment rejecting one of Medtronic’s counterclaims,
which asserted invalidity of claim 21. Then, based on an
agreement between the parties, it dismissed without
prejudice Medtronic’s other counterclaims, which asserted
invalidity of the ’734 patent’s other claims. For this court
to have jurisdiction in this appeal, we must find that
8                             ATLAS IP, LLC   v. MEDTRONIC, INC.

there is a final judgment before us, no other basis of
appellate jurisdiction being invoked or apparent.
    The legal question is whether the district court’s
complete adjudication of some claims followed by a con-
sented-to dismissal without prejudice of the remaining
claims—what has been called “manufactured finality”—
produces a final decision under § 1295(a)(1). The answer
hinges on whether we apply our law or the law of the
regional circuit, here the Eleventh Circuit. Under Elev-
enth Circuit law, the district court’s decision strongly
appears not to be final. See Hood v. Plantation Gen. Med.
Ctr., Ltd., 251 F.3d 932, 934 (11th Cir. 2001); State
Treasurer of State of Mich. v. Barry, 168 F.3d 8, 11 (11th
Cir. 1999). But our court has held that a final judgment
exists when a district court fully adjudicates some claims
and by consent dismisses all remaining counterclaims
without prejudice. See Doe v. United States, 513 F.3d
1348, 1353–54 (Fed. Cir. 2008); Nystrom v. TREX Co., 339
F.3d 1347, 1351 (Fed. Cir. 2003).
     Our own law, rather than regional-circuit law, gov-
erns on this issue. We apply our own law to issues unique
to patent law and regional circuit law to issues unrelated
to patent law. See Midwest Indus., Inc. v. Karavan Trail-
ers, Inc., 175 F.3d 1356, 1359 (Fed. Cir. 1999) (en banc in
relevant part). The statute governing our appellate
jurisdiction, § 1295, including in particular the language
giving us jurisdiction over an appeal from a “final deci-
sion” in a patent case, § 1295(a)(1), is unique to this court.
Although our interpretation of “final decision” is informed
by similar language in § 1291, which governs “courts of
appeals (other than the United States Court of Appeals
for the Federal Circuit),” § 1295 sets out the exclusive
jurisdiction of our circuit, and only our circuit. We there-
fore apply our own law to issues of finality under
§ 1295(a)(1). Nystrom, 339 F.3d at 1349–50. For that
reason, the district court’s order dismissing all pending
counterclaims without prejudice, after fully adjudicating
ATLAS IP, LLC   v. MEDTRONIC, INC.                        9

some of the claims, is final, see id. at 1351, and we have
jurisdiction here under § 1295(a)(1).
    We review a district court’s grant of summary judg-
ment de novo. Myers v. Bowman, 713 F.3d 1319, 1326
(11th Cir. 2013); Serdarevic v. Advanced Medical Optics,
Inc., 532 F.3d 1352, 1362 (Fed. Cir. 2008). We review the
claim construction rulings of the district court de novo
where, as here, there are no underlying factual issues.
See In re Papst Licensing Digital Camera Patent Litig.,
778 F.3d 1255, 1261 (Fed. Cir. 2015).
                                A
    Atlas does not dispute that the judgment of non-
infringement of claim 21 must be affirmed if, under the
“establishing” and “transmitting” limitations of clauses [b]
and [c], the endpoint of the communication cycle must be
communicated to the remotes before any remote trans-
mits frames to the hub. Infringement therefore turns
entirely on a claim-construction issue. When construing
claim terms, “[w]e generally give words of a claim their
ordinary meaning in the context of the claim and the
whole patent document; the specification particularly, but
also the prosecution history, informs the determination of
claim meaning in context, including by resolving ambigui-
ties; and even if the meaning is plain on the face of the
claim language, the patentee can, by acting with suffi-
cient clarity, disclaim such a plain meaning or prescribe a
special definition.” World Class Technology Corp. v.
Ormco Corp., 769 F.3d 1120, 1123 (Fed. Cir. 2014); see
Phillips v. AWH Corp., 415 F.3d 1303, 1312–17 (Fed. Cir.
2005) (en banc). Following that approach, we reject
Atlas’s challenge to the district court’s construction.
    Atlas attacks aspects of the threshold claim construc-
tion adopted by the district court in Atlas v. St. Jude
Medical, supra. It asserts that the ordinary meaning of
the word “establish” in the two limitations at issue is
merely “initiate,” so that the hub need not define the start
10                           ATLAS IP, LLC   v. MEDTRONIC, INC.

and duration of communication cycles and their intervals,
let alone transmit that definitional information. Atlas
Opening Br. 15–16. But, although “establish” might
mean “initiate” in some contexts, it must mean more in
this context, which is all about setting a schedule for
various communication devices to follow where coordina-
tion is important. A principal definition of “establish”
that most naturally fits this context is: “set up (an organi-
zation, system, or set of rules) on a firm or permanent
basis.” The New Oxford American Dictionary 580 (2001).
And although it is not clear that Atlas argues otherwise
independently of its “establish” contention, the context
also makes clear that the schedule thus established must
be “transmit[ted]” in advance of the start of the intervals
set up for remotes to transmit information to the hub.
    Claim 21 states that first the hub establishes commu-
nication cycles, which consist of three intervals: (a) when
the hub is allowed to transmit frames to the remotes, (b)
when the remotes are allowed transmit frames to the hub,
and (c) when each remote is expected to receive a frame
from the hub. ’734 patent, col. 50, lines 52–62. And then
the hub transmits information to the remotes to establish
those intervals. Id., col. 50, lines 55–62. If the hub does
not define the intervals when the hub will transmit to the
remotes and when each remote will transmit to the hub,
multiple communicators (e.g., the hub and a remote or
two remotes) could transmit simultaneously and their
signals would collide. See id., col. 3, lines 4–10. Thus, the
hub-sent information must indicate both the start and
end time of the intervals of each communication cycle.
    To fulfill the core claimed function of power saving,
each remote must know when its receiver and transmitter
can be off and must be on, which naturally, perhaps
necessarily, calls for the scheduling information to arrive
before any remote transmissions begin. The claim con-
firms that the transmittal of information must allow for
this power-saving function when it indicates, in language
ATLAS IP, LLC   v. MEDTRONIC, INC.                        11

mixing the plural and singular, that a remote powers off
its transmitter for times other than when it is allowed to
transmit, and similarly for the receiver for times when it
is expected to receive, “by using the information transmit-
ted from the hub.” Id., col. 50, line 63, through col. 51,
line 2. And the claim confirms the centrality of the timing
of the information transmittal when it adds a further
limitation requiring that the crucial information be
transmitted twice before remote transmissions begin: the
hub “transmitting two frames containing information to
establish the plurality of predeterminable intervals
during each communication cycle, the second frame
containing the information to establish[ ] the plurality of
predeterminable intervals occurring before the intervals
in which the remotes are allowed to transmit to the hub.”
Id., col. 51, lines 3–9. All of this makes clear that the hub
must set up a schedule of intervals and send that sched-
ule to the remotes before the transmission-opportunity
slots for the remotes arrive.
    The specification confirms that the interval allotment
must be defined (and communicated to the remotes)
before the remote-transmission opportunities begin. The
summary of the invention states that “[t]he hub transmits
control information to the remotes to establish the com-
munication cycle and to establish a plurality of predeter-
minable intervals during each communication cycle.” ’734
patent, col. 5, lines 47–50. That control information
“define[s] the starting times and durations of the subse-
quent intervals of the present communication cycle.” Id.,
col. 27, lines 57–61. Because the hub conveys those
“defined intervals” to the remotes, they are able to power
off their transmitters when they are not scheduled to
transmit and their receivers when they are not scheduled
to receive, and thereby achieve the significant battery-
saving power of the invention. Id., col. 5, lines 54–66; see
also id., col. 13, lines 12–14, 23–28, 29–36.
12                           ATLAS IP, LLC   v. MEDTRONIC, INC.

    Atlas does not seriously dispute that the specification
validates the district court’s construction, but instead
argues that the medium access control protocol, rather
than the hub, defines those intervals.           Atlas Re-
sponse/Reply Br. 5. The specification indicates, however,
that the hub uses a medium access control protocol as
part of its functionality, not that the medium access
control protocol performs any independent function. See
’734 patent, col. 11, lines 28–30 (describing the hub as
“control[ling] the communications to and from the re-
motes, using a MAC protocol”); id., col. 13, line 67,
through col. 14, line 2 (noting that one of the functions of
the hub is to serve as a “medium access control”). Thus,
both the claims and specification must be understood to
mean that the “establishing” and “transmitting” limita-
tions require the hub to define and transmit the start
time and duration of each communication cycle and its
constituent intervals in advance.
    Atlas invokes the doctrine of claim differentiation,
pointing to independent claims 1, 12, 14, and 34 as con-
taining more explicit references requiring the hub to
define intervals in advance. Atlas Opening Br. 16. Alt-
hough sometimes that doctrine (which counsels against
constructions that render some claim language superflu-
ous) is important in claim construction, it cannot support
Atlas’s position on claim construction here. The claims
invoked do not at all suggest any notion of establishing as
mere initiating. Moreover, each of the invoked claims
contains language that, under Atlas’s arguments, avoids a
conclusion of superfluousness under the construction of
the “establishing” and “transmitting” limitations at issue
here. 1 In any event, we have been cautious in assessing

     1  Claim 1 adds a requirement that “a frame” con-
tain relevant information. ’734 patent, col. 45, line 20.
Claim 12 adds requirements that further define how
ATLAS IP, LLC   v. MEDTRONIC, INC.                        13

the force of claim differentiation in particular settings,
recognizing that patentees often use different language to
capture the same invention, discounting it where it is
invoked based on independent claims rather than the
relation of an independent and dependent claim, and not
permitting it to override the strong evidence of meaning
supplied by the specification. See, e.g., World Class
Technology, 769 F.3d at 1126; Kraft Foods, Inc. v. Int’l
Trading Co., 203 F.3d 1362, 1368 (Fed. Cir. 2000). Here,
claim differentiation is not significant enough to alter our
conclusion on whether the claimed scheduling information
must be sent before remotes begin transmission.
     The district court did not decide in this case whether
the scheduling information (specifically, the starting time
and duration) must be sent before the communication
cycle begins or before the remotes begin transmitting. For
the reasons we have stated, that information must be sent
before the remotes begin transmitting, even apart from
the claim limitation requiring duplicate transmission
before remotes start transmitting. See ’734 patent, col.
51, lines 3–9 (“the hub transmitting two frames . . . , the
second frame containing the information to established
[sic] the plurality of predeterminable intervals occurring
before the intervals in which the remotes are allowed to
transmit to the hub”). The district court in this case
concluded that, as long as the information must be sent
before the remotes transmit, as we conclude it must,
Medtronic’s devices do not infringe. Atlas does not argue

certain transmission opportunities are allocated. Id., col.
49, lines 1–22. Claim 14 adds requirements about the
“length” of the communications cycle, id., col. 49, lines 63–
68, which Atlas has asserted differs from duration infor-
mation, J.A. 59–61. And claim 34 is similar. ’734 patent,
col. 54, lines 28–32.
14                           ATLAS IP, LLC   v. MEDTRONIC, INC.

otherwise. For that reason, we affirm the summary
judgment of non-infringement.
                             B
    A distinct issue of claim construction is presented by
the district court’s summary-judgment rejection of Med-
tronic’s invalidity challenges to claim 21. The court held
that language in clause [b], “communication cycles, each
of which has intervals during which the hub and the
remotes transmit and receive frames,” ’734 patent, col. 50,
lines 52–54, requires, as a matter of “plain meaning,” that
“the hub and the remotes transmit and receive frames
during each communication cycle, not that the hub and
the remotes simply may do so during a communication
cycle as Medtronic argues.” Atlas v. Medtronic, 2014 WL
5305577, at *3 (emphasis in original). We reject that
claim construction. We therefore reverse the grant of
summary judgment of no anticipation or obviousness,
which rested on the district court’s incorrect claim con-
struction.
    We note first that the district court’s construction is
ambiguous on its face. It might be read to require that, in
each cycle, every remote transmits a frame or, more
narrowly, that at least one remote does so. But neither
party suggests that the district court’s construction has
the every-remote meaning, and Atlas itself does not
suggest that the claim language can have that meaning.
Rather, both treat the district court as having agreed with
Atlas’s reading, expressly acknowledged by the district
court, id., that, during each cycle, at least one remote must
transmit a frame. See Medtronic Opening/Response Br.
26 (“The district court agreed with Atlas . . . .”). We
therefore focus on the at-least-one-remote interpretation.
But the reasons we reject that interpretation also require
rejection of the every-remote interpretation that no party
here attributes to the district court or defends as correct.
ATLAS IP, LLC   v. MEDTRONIC, INC.                      15

    The district court relied entirely on what it viewed as
the “plain meaning” of the claim language. Atlas v.
Medtronic, 2014 WL 5305577, at *3. The court thought
the meaning so plain that it did not even discuss any of
the contextual considerations that are often central to
claim construction. That was erroneous. The claim
language does not have the decisive plain meaning the
district court found, and contextual considerations point
compellingly the other way.
    The claim language at issue—stating that each cycle
“has intervals during which the hub and the remotes
transmit and receive frames,” ’734 patent, col. 50, lines
52–54—is the kind of phrase that is often used in ordi-
nary speech to set a general framework and not to com-
municate precise relations among its components. Here,
context must determine the relations of the intervals, the
hub and remotes, and the receiving and transmitting.
The imprecision of the language is apparent on its face.
For example, context aside, the plural “intervals” could
mean that what follows must occur “during” each interval:
both transmitting and receiving by both hub and “the
remotes.” It is context that precludes that interpretation:
hub actions and remote actions occur in separate inter-
vals. The plural “the remotes,” on its face, could mean
that all the remotes must perform the actions indicated.
But both parties agree that, in context, that reading
would be wrong.
    Ordinary usage of comparable expressions indicates
that the language here does not have a “plain meaning”
requiring some remote to transmit a frame in each cycle.
A statement that “each school day has classes during
which the teacher and students ask and answer ques-
tions” could easily be understood to describe what the
classes are set up to permit, even what generally goes on,
rather than that some student must ask a question in
each class. A statement about a multi-defendant trial
that “the trial has periods in which the prosecution and
16                           ATLAS IP, LLC   v. MEDTRONIC, INC.

the defendants put on and cross-examine witnesses”
would not necessarily mean that at least one defendant
must put on a witness. So, too, here: the claim language
does not “necessitate[ ]” that at least one remote must
transmit in each cycle. Atlas v. Medtronic, 2014 WL
5305577, at *3. Context must determine whether that is
a sound interpretation.
     The need for context-based interpretation is confirmed
by the imprecisions about plurals and conjunctions found
in claim language other than clause [b]. Clause [c] de-
scribes the intervals within each communication cycle as
“being ones” [1] “when” the hub is allowed to transmit
frames to the remotes, [2] “when” the remotes are allowed
transmit frames to the hub, [3] “and when” each remote is
expected to receive a frame from the hub. ’734 patent, col.
50, lines 55–62. The claim language is imprecise about
the conjunction “and”: the first two items in the three-
item list might or might not be mutually exclusive; the
first and third presumably are not mutually exclusive.
Only context resolves the facial uncertainty. In a similar
vein, clause [d] alternates between the plural “the re-
motes” and the singular “the remote” for no discernible
reason. It states, for example, that “the remotes power[]
off their transmitters during times other than those
intervals when the remote is allowed to transmit frames to
the hub.” Id., col. 50, lines 63–65 (emphases added).
Mixed use of singular and plural language is a recognized
source of likely ambiguity. See Robert C. Faber, Faber on
Mechanics of Patent Claim Drafting § 3:11 (7th ed. 2015).
Again, context is needed to obtain clarification.
    The district court did not rely on anything for its con-
struction except the claim words understood in isolation.
Neither has Atlas, in this court, identified any substantial
basis in the usual contextual considerations—notably,
other claim language and the specification—to support
the claim construction on which the district court’s validi-
ty ruling rests. In fact, as soon as the analysis widens its
ATLAS IP, LLC   v. MEDTRONIC, INC.                     17

focus to examine the context, the answer to the claim-
construction question here becomes clear: the language
sets aside times in which things are allowed to happen, as
in the sentences about classrooms and courtrooms noted
above. In particular, the claim language requires only
that each cycle have one or more intervals in which re-
motes are allowed to transmit.
    The other language of claim 21 strongly supports this
reading. It speaks of “intervals” “when the remotes are
allowed to transmit frames to the hub.” ’734 patent, col.
50, lines 58–61 (emphasis added). Again: “those intervals
when the remote is allowed to transmit frames to the
hub.” Id., col. 50, lines 64–65 (emphasis added). And
again: “the intervals in which the remotes are allowed to
transmit frames to the hub.” Id., col. 51, lines 8–9 (em-
phasis added). Many other claims of the patent are
similar. 2
    The specification does not contain any requirement
that at least one remote (much less all remotes) transmit
a frame during each communication cycle. Instead, the

    2   At oral argument, but not before, Atlas made a
claim-differentiation argument to the effect that its
construction of the language at issue here, which appears
as well in claim 14, would improperly give dependent
claim 17 the same scope as its independent claim (14).
That argument comes too late and is unpersuasive even
aside from the familiar cautions about claim differentia-
tion. Claim 17 refers to “length,” which Atlas has distin-
guished from duration, see note 1, supra, and requires
that the hub allocate transmission opportunities to the
remotes and adjust the length of the communication cycle
based on the number of transmission opportunities allo-
cated. Claim 17 is different from claim 14 regardless of
the claim-construction dispute concerning clause [b] of
claim 21.
18                           ATLAS IP, LLC   v. MEDTRONIC, INC.

specification explains that the remotes request transmis-
sion opportunities, which are “amount[s] of time during
which the remote may transmit one or more frames to the
hub.” ’734 patent, col. 12, lines 22–23 (emphasis added).
The specification clearly indicates that, if a remote does
not have any information to send, it may leave its trans-
mission opportunity unused. Id., col. 35, lines 9–11; id.,
col. 39, lines 18–20. Nothing in the specification pre-
cludes a full communication cycle in which no remote
transmits a frame because no remote has information to
send. The specification does not preclude that situation
expressly or by implication from the contemplated opera-
tion.
    In particular, no such requirement can be inferred
from Figure 19, which depicts a procedure according to
which remotes send control frames in the absence of
pending frames. Id., col. 44, lines 15–19. Figure 19
depicts only one embodiment. Indeed, that embodiment
has each remote sending a control frame each cycle—
which Atlas’s construction would not require. But the
specification makes clear that sending a control frame—
for various purposes—is optional. See id., col. 35, lines 9–
11 (“In the absence of any frames awaiting transmission,
the remote 66 may leave its [transmission opportunity]
unused, or may send a control frame.”); id., col. 39, lines
18–20 (same).
     Nor does the specification’s discussion of the hub go-
ing into an idle status imply the need for some remote to
transmit a frame in each cycle. The specification states
that the hub may go into an idle state “[i]f no transmis-
sions are received for a predetermined period of time
which is much longer than a communication cycle.” Id.,
col. 39, lines 63–67. By its terms, that discussion contem-
plates cycles with no remotes transmitting—indeed,
contemplates that there can be such cycles without the
hub going inactive.
ATLAS IP, LLC   v. MEDTRONIC, INC.                       19

    We therefore reject the district court’s construction of
the clause [b] claim language on which it relied to reject
Medtronic’s invalidity challenge to claim 21 on summary
judgment. We reverse the grant of summary judgment of
no anticipation or obviousness and remand for further
proceedings in light of the proper construction, requiring
only (as relevant here) that there be intervals in which
remotes are permitted to transmit frames.
                          CONCLUSION
    For the foregoing reasons, we affirm the district
court’s finding of non-infringement, reverse the district
court’s grant of summary judgment of no anticipation or
obviousness, and remand.
    Costs awarded to Medtronic.
 AFFIRMED IN PART, REVERSED IN PART, AND
               REMANDED