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IPCom GmbH & Co. v. HTC Corp.

United States Court of Appeals, Federal Circuit

July 7, 2017

IPCOM GMBH & CO., Appellant
v.
HTC CORPORATION, Appellee

         Appeal from the United States Patent and Trademark Office, Patent Trial and Appeal Board in No. 95/001, 192.

          Mitchell G. Stockwell, Kilpatrick Townsend & Stockton LLP, Atlanta, GA, argued for appellant. Also represented by Michael S. Pavento, David A. Reed.

          Michael A. Oblon, Perkins Coie, LLP, Washington, DC, argued for appellee. Also represented by TYLER R. Bowen, Jonathan M. James, Phoenix, AZ; Dan L. Bagatell, Hanover, NH.

          Before Prost, Chief Judge, Clevenger and Chen, Circuit Judges.

          Chen, Circuit Judge.

         IPCom GmbH & Co. (IPCom) is the owner of U.S. Patent No. 6, 879, 830 ('830 patent), which describes and claims a method and system for handing over a mobile phone call from one base station to another base station. After IPCom sued HTC Corporation (HTC) for infringing the '830 patent, HTC requested that the U.S. Patent and Trademark Office (PTO) conduct inter partes reexamination of claims 1, 5-26, and 28-37 of the '830 patent, which the PTO granted. The reexamination went through two rounds of review by the Examiner and the Patent Trial and Appeal Board (Board). In the first round, the Examiner concluded that the claims were patentable, but HTC appealed to the Board, which issued a new ground of rejection for claims 1 and 5-30. In the second round, IPCom amended claims 1, 5-26, and 28-37, [1] but the Board found that these amended claims were obvious under 35 U.S.C. § 103 in view of various combinations of McDonald, [2] Anderson, [3] GSM, [4] and PACS.[5]

         In its appeal, IPCom alleges that, even though it had amended the scope of claims 31-37 during its second round before the Examiner, the Board lacked jurisdiction to review the Examiner's patentability determination of these amended claims in the Board decision now on appeal. IPCom also argues that the Board's obviousness rejections were based on a flawed claim construction, because the Board never identified the structure in the patent specification that corresponds to the "arrangement for reactivating the link" means-plus-function claim limitation. IPCom also appeals the Board's factual findings for several other claim limitations and the motivation to combine the prior art references in the manner claimed by the '830 patent.

         We conclude that, under the circumstances of this case, the Board properly had the authority to consider the patentability of claims 31-37 and thus reject IPCom's procedural challenge to the Board's rejection of these claims. But we agree with IPCom that the Board failed to conduct a proper claim construction of the "arrangement for reactivating the link" claim limitation, and we vacate and remand the obviousness rejections based on that limitation. We affirm the Board's findings in all other respects.

         Background

         The '830 patent describes a method for performing handover (or handoff) of a cellular telephone or mobile station (MS) in a cellular telephone network from a first base station (BSl) to a second base station (BS2). '830 patent col. 1 ll. 14-62. Mobile stations communicate with a network by exchanging signals with a base station, where the base station is part of a wired network of base stations, fixed lines, and switching units. Id. col. 2 1. 64-col. 3 1. 3. Handover occurs in a network when the mobile station switches from one base station to another. Id. col. 1 ll. 25-28.

         The '830 patent describes forward and forced handover techniques. Id. col. 5 ll. 10-15, 61-64. A forward handover is one in which the mobile station, rather than the first base station, determines a handover is necessary, and seeks out the second base station. Id. col. 1 ll. 37-38. A forced handover is one in which the first base station initiates the handover, e.g., by sending a message to the mobile station instructing the mobile station to perform a handover to a second base station. Id. col. 1 ll. 53-56, col. 2 ll. 24-31.

         To reduce the chance of interrupted service when a mobile station must perform a handover, the claimed invention calls for the first base station to maintain, for a period of time, the link data for the mobile station as well as hold in reserve link resources required to maintain a link between the mobile station and the first base station. When a handover of the mobile station to a second base station is unsuccessful, the mobile station reactivates the link with the first base station, e.g., by continuing to maintain the link. Id. col. 2 ll. 38-40, col. 5 ll. 10-15, 61-64, col. 6 ll. 13-53. By providing this feature, if the mobile station cannot establish a link with a second base station, the mobile station's link with the first base station can be maintained without the mobile base station having to resend link information to the first base station. Id. col. 5 ll. 24-26, col. 6 ll. 40-52. This feature is claimed in the "arrangement for reactivating the link" limitation in independent claims 1, 18, 30, and 34. J.A. 12565-74. Claim 1 is reproduced below:

1. (Unamended) A mobile station for use with a network including a first base station and a second base station that achieves a handover from the first base station to the second base station by:
storing link data for a link in a first base station,
holding in reserve for the link resources of the first base station, and
when the link is to be handed over to the second base station:
initially maintaining a storage of the link data in the first base station,
initially causing the resources of the first base station to remain held in reserve, and
at a later timepoint determined by a fixed period of time predefined at a beginning of the handover, deleting the link data from the first base station and freeing up the resources of the first base station, the mobile station comprising:
an arrangement for reactivating the link with the first base station if the handover is unsuccessful.

J.A. 12565 (emphasis added). Independent claims 18, 30, and 34 also recite three additional limitations of (1) a "forced handover request message" from the first base station to the mobile station; (2) a "handover query" from the mobile station to a second base station; and (3) a "rejection message" from the second base station if the second base station cannot support the mobile station. Appellant Br. 10-11; J.A. 12570-74.

         The '830 patent also describes a flexible type of handover, in which a handover is handled in different ways, depending on whether a network can support handover by transferring "link data" directly between the first and second base stations, or whether that information must be communicated directly from the mobile station to the second base station. '830 patent col. 2 ll. 32-38, col. 3 ll. 10-16. This feature is the "informing the mobile station" limitation recited in independent claims 5, 12, and 16. J.A. 12566-70. Claim 5, for example, recites "informing the mobile station whether the network is capable of transferring the link data from the first base station to the second base station." J.A. 12567. The last relevant limitation in the challenged claims covers a network using different generations of radio communication standards and is recited in claims 23 and 25. J.A. 12571-72. These claims recite that "the first base station and the second base station operate in respective parts of the network using different generations of radiocommunications standards for radio communication with the mobile station." J.A. 12571-72.

         For purposes of this appeal, the challenged claims can be separated into five categories. First, independent claims 1, 18, 30, and 34 recite the "arrangement for reactivating the link" means-plus-function limitation. Second, independent claims 18, 30, and 34 recite the "forced handover request message, " "handover query, " and "rejection message" limitations. Third, independent claims 5, 12, and 16 recite the "informing the mobile station" limitation. Fourth, dependent claims 23 and 25 recite using different generations of radio communications standards. Fifth, claims 31-37 are challenged based on jurisdiction.

         I. McDonald

         As noted, the Board considered four prior art references. McDonald describes a technique for dealing with failed handovers. When a mobile station moves from one cell to a neighboring cell in a cellular telephone network, the mobile station searches for a second base station in the neighboring cell and sends an inbound signaling word (ISW) message to inquire whether a handover is possible. McDonald col. 1 ll. 30-33, col. 2 1. 66-col. 3 1. 9. If the second base station cannot support a handover, the network sends the mobile station a busy outbound signaling word (OSW) rejection message. Id. col. 1 ll. 42-46, col. 2 ll. 1-3). The "busy OSW" signal informs the mobile station that the network cannot transfer link data from the first base station to the second base station. J.A. 7. The mobile station "can then choose to return" to the first base station by "deregister[ing]" from the second base station, "inform[ing]" the network that it is "returning to the previous channel, " and "attempting] to receive" at the first base station. McDonald col. 3 ll. 14-21.

         II. Anderson

         Anderson describes "mobile directed" or "mobile centric" handover techniques. Anderson col. 17 ll. 45-52. Anderson describes integrating multiple cellular network technologies, including GSM (prior art reference described infra at Background Part III) into a single network. Id. col. 4 ll. 40-61. It also describes several types of successful handovers, including a "make before break" handover. Id. col. 15 l. 25-col. 18 l. 25. In this handover, the mobile station initiates a handover attempt based on a drop in link quality below a predetermined threshold level between the mobile station and a first base station. Id. col. 16 ll. 26-33. To initiate the handover, the mobile station scans for potential new base stations and measures the received signal quality from the potential new base stations to identify a base station with the highest signal quality (the second base station). Id. col. 16 ll. 6-30. The mobile station then sends a handover request message to the second base station and waits for a response. Id. col. 16 ll. 26-33. If the second base station accepts the mobile station's handover request, the second base station sends a response requesting transfer of the link data from the first base station to the second base station, and the network transfers the link data. Id. col. 16 ll. 36-60. By transferring the link data from the first base station to the second base station, the network informs the mobile station that the network can transfer the link data.

         Anderson also describes a "break before make" embodiment to prevent interrupted service. Anderson col. 18 ll. 16-21. In this embodiment, a mobile station that suddenly loses its connection with a first base station can quickly reacquire the first base station, or acquire a different base station (even if no information is available after the link with the first base station is lost). Id. col. 18 ll. 16-21.

         III. Global System for Mobile (GSM) Communications

         The Global System for Mobile (GSM) communications standard was developed by the European Telecommunications Standards Institute (ETSI) to standardize telecommunications protocols. J.A. 13225. GSM describes reactivating a link with a first base station when a handover attempt to a second base station is unsuccessful. The mobile station sends a "channel request" message to a second base station, which responds, in some circumstances, with an "immediate assignment reject" message. J.A. 13303. The mobile station then sends a "handover failure" message to the first base station and "resumes normal operation as if no handover attempt had occurred." Id. GSM also describes the use of base stations that can operate using different generations of radio communications standards because it discloses a mobile station ...


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