Ex Parte Armitage

Board of Patent Appeals and Interferences

Sep 4, 2009

09824960 (B.P.A.I. Sep. 4, 2009)

UNITED STATES PATENT AND TRADEMARK OFFICE
__________

BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
__________

Ex parte GRENVILLE J. ARMITAGE
__________

Appeal 2008-004803
Application 09/824,960
Technology Center 2400
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Decided: September 4, 2009
__________

Before JAMES D. THOMAS, LEE E. BARRETT, and STEPHEN C. SIU,
Administrative Patent Judges.

SIU, Administrative Patent Judge.

DECISION ON APPEAL

STATEMENT OF THE CASE
This is a decision on appeal under 35 U.S.C. § 134(a) from the
Examiner’s rejection of claims 1-14. We have jurisdiction under 35 U.S.C.
§ 6(b).
We reverse.
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Invention
The invention relates generally to a technique to enable mobile nodes
or hosts to communicate with other nodes associated with a wired
information network, notwithstanding changes in the mobile hosts’ points of
attachment to the network (Spec. 1). This technique includes identifying a
first interface of a home router and the mobile hosts with corresponding
unicast network addresses, and identifying a second interface of the home
router with a corresponding unicast network address (id. at 3-4). The first
interface of the home router and the mobile hosts are assigned corresponding
group addresses according to a given relation with respect to the unicast
network addresses (id. at 4). Unicast addresses of packets received at the
second interface and destined to members of the subnet, are mapped to the
group addresses assigned to the members of the subnet (id.).
Independent claim 1 is illustrative:
1. A method of supporting a mobile host on an information network
configured for multicast routing, comprising:
defining a subnet (U1) of the network that includes one or more
mobile hosts and a first interface of a home router in the
network, and identifying the first interface and the mobile hosts
with corresponding unicast network addresses (U1.x);
identifying a second interface of the home router with a
corresponding unicast network address (U2.x);
assigning the first interface of the home router and the mobile
hosts corresponding group addresses (Mx) according to a
defined relation with respect to said unicast network addresses;
mapping, at the second interface of the home router, unicast
addresses of packets received at the second interface and
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destined to members of the subnet (U1), to the group addresses
(Mx) assigned to the members of the subnet;
linking the mobile hosts with the network at corresponding
points of attachment; and
sending a request from a given mobile host to join a group
corresponding to a group address assigned to the given mobile
host each time the mobile host links with the network at a new
point of attachment, thereby enabling routers in the network to
track the mobile host as it moves its link with the network from
one point of attachment to another, and to route unicast packets
originating from a host outside the subnet and destined to a
given mobile host, by way of a virtual link defined between the
home router and the given mobile host.

References
The Examiner relies upon the following references as evidence in
support of the rejections:
Reid US 6,131,120 Oct. 10, 2000
Harvey US 6,189,039 B1 Feb. 13, 2001

C. Perkins, IP Mobility Support, RFC 2002, Internet Engineering Task
Force (IETF) (Oct. 1996), available at
http://www.ietf.org/rfc/rfc2002.txt (“Perkins”).

Rejection
Claims 1, 2, and 4-14 are rejected under 35 U.S.C. § 103(a) as being
unpatentable over Perkins and Harvey.
Claim 3 is rejected under 35 U.S.C. § 103(a) as being unpatentable
over Perkins, Harvey, and Reid.
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ISSUE
Appellant argues
that there is no motivation to combine Perkins with Harvey. Perkins
may arguably be related to the tracking of a mobile device. However,
Harvey is unrelated to such tracking. There is simply no hint or
suggestion in Harvey that the users which are part of its computer
network are mobile or if they are mobile that they need to be tracked.

(App. Br. 28).
Issue: Has Appellant shown that the Examiner erred by relying upon
impermissible hindsight in combining Perkins and Harvey for enabling
tracking of a mobile host as it moves its link with a network from one point
of attachment to another through mapping of packets received at a unicast
network address to a group address?
FINDINGS OF FACT
The following Findings of Fact (FF) are shown by a preponderance of
the evidence.
1. Perkins teaches
protocol enhancements that allow transparent routing of IP
[Internet Protocol] datagrams to mobile nodes in the Internet.
Each mobile node is always identified by its home address,
regardless of its current point of attachment to the Internet.
While situated away from its home, a mobile node is also
associated with a care-of address, which provides information
about its current point of attachment to the Internet. The
protocol provides for registering the care-of address with a
home agent. The home agent sends datagrams destined for the
mobile node through a tunnel to the care-of address. After
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arriving at the end of the tunnel, each datagram is then
delivered to the mobile node.
(Abstract).
2. Perkins teaches that
[w]hen a mobile node detects that it has moved to a foreign
network, it obtains a care-of address on the foreign network.

. . . .

A “foreign agent care-of address” is a care-of address provided
by a foreign agent through its Agent Advertisement messages.
In this case, the care-of address is an IP address of the foreign
agent. . . .

A “co-located care-of address” is a care-of address acquired by
the mobile node as a local IP address through some external
means, which the mobile node then associates with one of its
own network interfaces. . . . Specific external methods of
acquiring a local IP address for use as a co-located care-of
address are beyond the scope of this document.
(§ 1.7. Protocol Overview).
3. Perkins teaches that a home agent can provide a capability to
“maintain multiple simultaneous registrations, so that a copy of each
datagram will be tunneled to each active care-of address” (§ 3.
Registration).
4. Perkins teaches that
In order receive [sic] multicasts [when visiting a foreign
network], a mobile node MUST join the multicast group in one
of two ways. First, a mobile node MAY join the group via a
(local) multicast router on the visited subnet. . . .

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Alternatively, a mobile node which wishes to receive multicasts
MAY join groups via a bi-directional tunnel to its home agent,
assuming that its home agent is a multicast router.
(§ 4.4. Multicast Datagram Routing).
5. Harvey “generally relates to data transmissions in computer
networks and, in particular, to a method for selective streaming of
data (e.g. video) using multiple transmission protocols” (col. 1,
ll. 6-9).
6. Harvey teaches that the objects of the invention include
“minimize[ing] network traffic in a computer network by providing an
efficient data streaming method”; “enhance[ing] the efficiency of data
transport over a computer network using known unicasting and
multicasting techniques”; “us[ing] IP unicast and IP multicast
protocols to stream the same data to multiple users in a computer
network in a manner that minimizes network traffic”; “provid[ing]
selective streaming of video data from a video server to end users in a
computer network such as an enterprise intranet”; “enhance[ing]
bandwidth utilization in a computer network transparently to the end
user”; and “enhance[ing] the transmission of video data streams
across multiple segments of a computer network” (col. 1, ll. 62-67;
col. 2, ll. 1-14).
7. Harvey teaches that
[o]ne of the servers generates data, such as video content, that is
desired to be received and viewed at one or more clients. To
this end, it is known in the prior art to provide a so-called
“tunneler” utility and, if needed, a “repeater” utility. For
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illustrative purposes, each of the network segments may be
assumed to have its own tunneler 15 and one or more repeaters
17. The tunneler utility . . . receives an IP multicast signal and
converts the signal to IP unicast format for delivery to an end
user. The repeater utility . . . functions to receive an IP unicast
signal and convert the signal to IP multicast format for delivery
to other end users.
(Col. 3, ll. 25-40; FIG. 1).
PRINCIPLES OF LAW
Obviousness
The question of obviousness is resolved on the basis of underlying
factual determinations including (1) the scope and content of the prior art,
(2) any differences between the claimed subject matter and the prior art, and
(3) the level of skill in the art. Graham v. John Deere Co., 383 U.S. 1, 17-
18 (1966).
“A factfinder should be aware, of course, of the distortion caused by
hindsight bias and must be cautious of arguments reliant upon ex post
reasoning.” KSR Int’l Co. v. Teleflex, Inc., 550 U.S. 398, 421 (2007). “[A]
patent composed of several elements is not proved obvious merely by
demonstrating that each of its elements was, independently, known in the
prior art.” Id. at 418. Helpful insights, such as identifying a “teaching,
suggestion, or motivation to combine” can be useful tools in avoiding
erroneous rejections. Id. However, care must be taken not to allow such
helpful insights to become “[r]igid preventative rules that deny factfinders
recourse to common sense.” Id. at 421.
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ANALYSIS
In support of the combinability of Perkins and Harvey, the Examiner
argues that Appellant fails
to fully appreciate the significance of Harvey’s teachings, interpreting
them in too narrow of a light, where it would have been obvious to
one of ordinary skill in the art that they have broader implications. . . .
Although Harvey fails to specify that the nodes in a subnet may be
mobile hosts . . . the teachings of Harvey have obvious applications in
a network having mobile hosts.

(Ans. 9). We do not agree with the Examiner’s reasoning.
Perkins teaches protocol enhancements to allow transparent routing of
IP (Internet Protocol) datagrams to a mobile host (FF 1). This is
accomplished by having a home agent send datagrams destined for the
mobile host through a tunnel to the mobile host’s care-of address (FF 1).
Mobile hosts use either a foreign agent care-of address, provided by a
foreign agent, or a co-located care-of-address, a local IP address acquired
through some external means, which the mobile host associates with one of
its own network interfaces (FF 2). Perkins notes that the external methods
of acquiring a local IP address for use as a co-located care-of address are
beyond the scope of the teachings of Perkins (FF 2).
Missing from Perkins is any suggestion that the care-of address for a
mobile host can be a group (or multicast) IP address. This is notable given
that Perkins discusses home agents sending copies of datagrams to multiple
registered care-of addresses (FF 3) and techniques for mobile hosts to join
multicast groups (FF 4). Perkins touches on both these topics, but fails to
discuss having a home agent send datagrams to a group care-of address to
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enable tracking of a mobile host as it moves from one point of attachment to
another.
The Examiner argues that while Perkins fails to specifically disclose
the mapping of unicast addresses received at a second interface to group
addresses of a first interface, Harvey teaches the missing limitations (Ans.
9). Furthermore, the Examiner argues that it would have been obvious to
one of ordinary skill in the art to use Harvey’s teachings to fill in these
missing limitations (id.).
Harvey’s teachings are generally related to data transmissions in
computer networks (FF 5). Specifically, they are related to streaming of
data such as video (FF 5). Significantly, every object of Harvey relates
either to data transmission efficiency (e.g., minimizing network traffic) or
transmitting video data streams (FF 6).
These objects are distinct from the present invention’s object of
enabling tracking of mobile devices. Moreover, Harvey’s teachings of
mapping a unicast IP signal to IP group format is shown in the context of
transmitting data, between network segments, destined for multiple clients
(FF 7).
To combine Perkins and Harvey in the manner suggested by the
Examiner, an artisan would have had to recognize that the care-of addresses
of Perkins could be group addresses or that the teachings of Harvey could be
used to track a single mobile node traveling among network segments
(instead of simply improving data transmission efficiency to multiple
nodes). Perkins discusses topics related to transmission of data to a mobile
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node through multiple care-of IP addresses and to enabling a mobile node to
receive group transmissions. Yet Perkins fails to teach or suggest a group
care-of IP address, suggesting that group care-of IP addresses are
nonobvious. Harvey focuses on data stream transmission to multiple clients
without addressing the possibility of a single node using the same group
address to receive data when connected to different network segments.
Because of this focus, one of ordinary skill in the art would be unlikely to
appreciate the broader significance of Harvey to the extent argued by the
Examiner.
Based upon our review of the evidence before us, we are unconvinced
that even an artisan possessing creativity and common sense, and having
knowledge of mobile node routing and group address technologies, would
have reasonably combined Perkins and Harvey in the manner suggested by
the Examiner, but for having the benefit of the instant claims to
impermissibly use as a guide.
Accordingly, we find Appellant has met the burden of showing the
Examiner erred in rejecting claims 1-14.
CONCLUSION
Based on the findings of facts and analysis above, we find Appellant
has demonstrated the Examiner erred by relying upon impermissible
hindsight in combining Perkins and Harvey for enabling tracking of a mobile
host as it moves its link with a network from one point of attachment to
another through mapping of packets received at a unicast network address to
a group address.
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DECISION
We reverse the Examiner’s decisions rejecting claims 1-14.

REVERSED

msc

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