TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

Patent Trials and Appeals Board

Sep 30, 2020

2019003595 (P.T.A.B. Sep. 30, 2020)

UNITED STATES PATENT AND TRADEMARK OFFICE
UNITED STATES DEPARTMENT OF COMMERCE
United States Patent and Trademark Office
Address: COMMISSIONER FOR PATENTS
P.O. Box 1450
Alexandria, Virginia 22313-1450
www.uspto.gov
APPLICATION NO. FILING DATE FIRST NAMED INVENTOR ATTORNEY DOCKET NO. CONFIRMATION NO.
15/306,806 10/26/2016 Rasmus AX¿N P47478 US2 5460
27045 7590 09/30/2020
ERICSSON INC.
6300 LEGACY DRIVE
M/S EVR 1-C-11
PLANO, TX 75024
EXAMINER
KIM, MINJUNG
ART UNIT PAPER NUMBER
2644
NOTIFICATION DATE DELIVERY MODE
09/30/2020 ELECTRONIC
Please find below and/or attached an Office communication concerning this application or proceeding.
The time period for reply, if any, is set in the attached communication.
Notice of the Office communication was sent electronically on above-indicated "Notification Date" to the
following e-mail address(es):
amber.rodgers@ericsson.com
michelle.sanderson@ericsson.com
pam.ewing@ericsson.com
PTOL-90A (Rev. 04/07)
UNITED STATES PATENT AND TRADEMARK OFFICE
BEFORE THE PATENT TRIAL AND APPEAL BOARD
Ex parte RASMUS AXEN and KARL NORRMAN
Appeal 2019-003595
Application 15/306,806
Technology Center 2600
BEFORE CAROLYN D. THOMAS, MICHAEL J. STRAUSS, and
JEREMY J. CURCURI, Administrative Patent Judges.
CURCURI, Administrative Patent Judge.
DECISION ON APPEAL
STATEMENT OF THE CASE
Pursuant to 35 U.S.C. § 134(a), Appellant1 appeals from the
Examiner’s decision to reject claims 1, 2, 4–13, 41, 42, and 44–53. We have
jurisdiction under 35 U.S.C. § 6(b).
We AFFIRM IN PART.

1 We use the word Appellant to refer to “applicant” as defined in 37 C.F.R.
§ 1.42(a). Appellant identifies the real party in interest as
Telefonaktiebolaget LM Ericsson. Appeal Br. 1.
Appeal 2019-003595
Application 15/306,806

2
CLAIMED SUBJECT MATTER
The claims are directed to “techniques relating to the handover of a
terminal device between radio access nodes in [a] communication network.”
Spec. 1:4–6. Claim 1, reproduced below, is illustrative of the claimed subject
matter:
1. A method of operating a first radio access node in
a communication network, the method comprising:
determining whether a first base key that is used to
determine a first encryption key for encrypting communications
between a communication device and the first radio access node
can be used by a second radio access node for determining a
second encryption key for encrypting communications between
the communication device and the second radio access node;
and
if the first base key can be used by the second radio
access node, sending the first base key to the second radio
access node during handover of the communication device from
the first radio access node to the second radio access node; and
if the first base key cannot be used:
determining a second base key from the first base
key; and
sending the second base key to the second radio
access node during handover of the communication
device from the first radio access node to the second
radio access node.
REFERENCES
The prior art relied upon by the Examiner is:
Appeal 2019-003595
Application 15/306,806

3
Name Reference Date
Cheng US 6,418,130 B1 July 9, 2002
Barany US 2009/0041247 A1 Feb. 12, 2009
Brusilovsky US 2009/0220087 A1 Sept. 3, 2009
Hahn US 2009/0307496 A1 Dec. 10, 2009

REJECTIONS2
Claims 1, 5–9, 41, and 45–49 are rejected under 35 U.S.C. § 103 as
unpatentable over Cheng and Brusilovsky. Final Act. 11–20.
Claims 2 and 42 are rejected under 35 U.S.C. § 103 as unpatentable
over Cheng, Brusilovsky, and Hahn. Final Act. 20–21.
Claims 4, 10, 44, and 50 are rejected under 35 U.S.C. § 103 as
unpatentable over Cheng, Brusilovsky, and Barany. Final Act. 22–23.
Claims 11–13 and 51–53 are rejected under 35 U.S.C. § 103 as
unpatentable over Barany and Brusilovsky. Final Act. 23–29.
OPINION
The Obviousness Rejection of Claims 1, 5–9, 41, and 45–49
over Cheng and Brusilovsky
The Examiner finds the combined teachings of Cheng and
Brusilovsky teach all limitations of claim 1. Final Act. 11–15; see also Ans.
3–11.
In particular, the Examiner finds Cheng teaches “determining whether
a first base key that is used to determine a first encryption key . . . can be

2 The rejection of claims 1, 2, 4–13, 41, 42, and 44–53 under 35 U.S.C.
§ 112(b) (Final Act. 9–10) has been withdrawn. Ans. 3.
Appeal 2019-003595
Application 15/306,806

4
used by a second radio access node for determining a second encryption
key,” as recited in claim 1. See Final Act. 11–12.
The Examiner finds Brusilovsky teaches “determining a second base
key from the first base key; and sending the second base key to the second
radio access node during handover of the communication device from the
first radio access node to the second radio access node.” See Final Act. 13–
14. The Examiner reasons “[i]t would have been obvious to one skilled in
the art to substitute one encryption key derivation method . . . with another
encryption key derivation method . . . to achieve the predictable result of
deriving encryption key for secure communication during handover.” Final
Act. 14; see also Final Act. 15.
Appellant presents the following principal arguments:
i. Cheng does not teach “determining whether a first base key that
is used to determine a first encryption key . . . can be used by a second radio
access node for determining a second encryption key” as recited in claim 1.
See Appeal Br. 8–11; see also Reply Br. 2–4. “[D]etermining whether or not
a second [network stationary unit (SU)] is part of the same administrative
domain is not literally the same as determining whether or not the second SU
can use a first base key.” Appeal Br. 9. “[A]ll the SU in Cheng determines is
whether or not the other SU is part of the same administrative domain as
itself—it does not determine whether or not any of the security associations
can be re-used.” Appeal Br. 9. “The fact that two particular SUs are under
the control of a common security policy and are managed in an identical
manner does not mean they can both use the same base key.” Appeal Br. 9.
ii. Cheng does not teach the first radio access node makes the
determination. See Appeal Br. 11–12; see also Reply Br. 5–6. “[I]n Cheng it
Appeal 2019-003595
Application 15/306,806

5
is the target SU that verifies the administrative domain, not the source SU.”
Appeal Br. 11.
iii. The combination of Brusilovsky and Cheng requires more than
a simple substitution. See Appeal Br. 12–13; see also Reply Br. 7–8.
[I]f the key encryption of Brusilovsky were to be used with
Cheng, the source SU would always send the newly derived
KeNB*, not the KeNB used by the source SU. If the target SU
does not receive the KeNB actually used by the source SU, the
target SU is not able to use the same KeNB used by the source
SU, even if both SUs are part of the same administrative domain.
Appeal Br. 13.
We do not see any error in the contested Examiner’s findings. We
concur with the Examiner’s conclusion of obviousness.
Regarding Appellant’s argument (i), Cheng discloses “SUk 105 then
replies to the SA request message by sending the appropriate SA attributes
to SUk+l 110.” Cheng, col. 5, ll. 40–41. Cheng further discloses “the step of
verifying that SUk belongs to the same administrative domain as SUk+1.”
Cheng, col. 5, ll. 45–46. Thus, Cheng discloses re-use of security
associations when the new stationary unit (SU) and the old stationary unit
(SU) belong to the same administrative domain. See Cheng, col. 5, ll. 40–41,
45–46. In this disclosure, Cheng’s determination is equivalent to the claimed
determination and, thus, Cheng teaches “determining whether a first base
key that is used to determine a first encryption key . . . can be used by a
second radio access node for determining a second encryption key” as
recited in claim 1. Accordingly, Appellant’s argument (i) does not show any
error in the Examiner’s findings.
Appeal 2019-003595
Application 15/306,806

6
Regarding Appellant’s argument (ii), this argument is unavailing
because the language of claim 1 does not require the first radio access node
to make the determination, and we interpret claim 1 as encompassing
arrangements where the determination is made by something other than the
first radio access node, such as the target SU in Cheng. See Claim 1, Cheng,
col. 5, ll. 45–46. Accordingly, Appellant’s argument (ii) does not show any
error in the Examiner’s findings.
Regarding Appellant’s argument (iii), this argument does not show
any error because we disagree with Appellant’s interpretation of the
combined teachings of Cheng and Brusilovsky. The Examiner finds Cheng
teaches “sending the first base key to the second radio access node,” as
recited in claim 1. Final Act. 12 (citing Cheng, Fig. 1). The Examiner further
finds Brusilovsky teaches “sending the second base key to the second radio
access node,” as recited in claim 1. Final Act. 13 (citing Brusilovsky, Fig. 4).
Together, Cheng and Brusilovsky teach all claim limitations. The Examiner
articulated a reason to combine Cheng and Brusilovsky that is rational on its
face and supported by evidence drawn from the record. See Final Act. 14–15
(citing Brusilovsky Abstract). Appellant has not presented any particularized
arguments as to why this reasoning is incorrect. Accordingly, Appellant’s
argument (iii) does not show any error in the Examiner’s findings.
We, therefore, sustain the Examiner’s rejection of claim 1.
We also sustain the Examiner’s rejection of claims 5–9, which are not
separately argued with particularity.
However, unlike claim 1, independent claim 41 requires the first radio
access node to make the determination. See Claim 41 (“whereby said first
radio access node is operative to: determine”). Here, we find Appellant’s
Appeal 2019-003595
Application 15/306,806

7
argument (ii) persuasive of Examiner error. Apparently recognizing the
merits of Appellant’s argument (ii), in the Examiner’s Answer, the Examiner
determines “[i]t would have been obvious to one of ordinary skill in the art
to have modified the teaching of method performed at the target SU
[(SUk+1)] to function at the source SU [(SUk)].” Ans. 7. However, on the
record before us, we do not see sufficient support for such a modification to
Cheng. Further, we do not agree with the Examiner’s characterization of
Brusilovsky on page 7 of the Examiner’s Answer because Brusilovsky
appears to send the new key without making a determination as claimed. See
Brusilovsky, Fig. 4.
We, therefore, do not sustain the Examiner’s rejection of claim 41.
We also do not sustain the Examiner’s rejection of claims 45–49,
which depend from claim 41.

The Obviousness Rejection of Claims 2 and 42 over
Cheng, Brusilovsky, and Hahn
Appellant does not present arguments with respect to this ground of
rejection. See Appeal Br. 8–13; see also Reply Br. 2–8.
We, therefore, sustain the Examiner’s rejection of claim 2.
Claim 42 depends from claim 41. The Examiner does not find Hahn
cures the deficiency of Cheng and Brusilovsky discussed above when
addressing claim 41. See Final Act. 20–21; see also Ans. 6–8.
We, therefore, do not sustain the Examiner’s rejection of claim 42.

Appeal 2019-003595
Application 15/306,806

8
The Obviousness Rejection of Claims 4, 10, 44, and 50 over
Cheng, Brusilovsky, and Barany
Appellant does not present arguments with respect to this ground of
rejection. See Appeal Br. 8–13; see also Reply Br. 2–8.
We, therefore, sustain the Examiner’s rejection of claims 4 and 10.
Claim 44 and 50 depends from claim 41. The Examiner does not find
Barany cures the deficiency of Cheng and Brusilovsky discussed above
when addressing claim 41. See Final Act. 22–23; see also Ans. 6–8.
We, therefore, do not sustain the Examiner’s rejection of claims 44
and 50.

The Obviousness Rejection of Claims 11–13 and 51–53 over
Barany and Brusilovsky
Appellant does not present separate arguments with respect to this
ground of rejection. See Appeal Br. 8–13; see also Reply Br. 2–8.
The arguments related to Cheng are not applicable here because this
ground of rejection does not rely on Cheng.
We, therefore, sustain the Examiner’s rejection of claims 11–13 and
51–53.
CONCLUSION
The Examiner’s decision to reject claims 1, 2, 4–13, 41, 42, and 44–
53 is affirmed in part.
Appeal 2019-003595
Application 15/306,806

9
DECISION SUMMARY
In summary:
Claims
Rejected
35 U.S.C.
§
Reference(s)/Basis Affirmed Reversed
1, 5–9, 41,
45–49
103

Cheng,
Brusilovsky
1, 5–9 41, 45–49
2, 42 103 Cheng,
Brusilovsky, Hahn
2 42
4, 10, 44, 50 103 Cheng,
Brusilovsky,
Barany
4, 10 44, 50
11–13, 51–
53
103 Barany,
Brusilovsky
11–13, 51–
53

Overall
Outcome
1, 2, 4–13,
51–53
41, 42, 44–
50

TIME PERIOD FOR RESPONSE
No time period for taking any subsequent action in connection with
this appeal may be extended under 37 C.F.R. § 1.136(a). See 37 C.F.R.
§ 1.136(a)(1)(iv).
AFFIRMED IN PART