PTAB Narrows Its Preliminary Claim Interpretation To Uphold Cellular Patent
In July, 2014 Ericsson Inc. and Telefonaktiebolaget LM Ericsson (“Ericsson”) petitioned for inter partes review of claims 1, 2, 8-12 and 18-22 of U.S. Patent No. 7,787,431 owned by Intellectual Ventures II LLC (“IV”). In February, 2015, the Board instituted trial on claims 1 and 2 based on obviousness grounds, but denied institution of obviousness grounds for claims 8-12 and 18-22. In a final written decision dated January 29, 2016, claims 1 and 2 of the ’431 patent were determined to be unpatentable. (IPR2014-01195, Paper 37.)
Ericsson filed a second IPR petition in August, 2015, again challenging claims 8-12 and 18-22. (IPR2015-01664, August 3, 2015.) Claim 8 is representative:
8. A cellular base station comprising:
circuitry configured to transmit a broadcast channel in an orthogonal frequency division multiple access (OFDMA) coreband, wherein the core-band is substantially centered at an operating center frequency and the core-band includes a first plurality of subcarrier groups, wherein each subcarrier group includes a plurality of subcarriers, wherein the core-band is utilized to communicate a primary preamble sufficient to enable radio operations, the primary preamble being a direct sequence in the time domain with a frequency content confined within the core-band or being an OFDM symbol corresponding to a particular frequency pattern within the core-band,
wherein properties of the primary preamble comprise:
an autocorrelation having a large correlation peak with respect to sidelobes;
a cross-correlation with other primary preambles having a small cross-correlation coefficient with respect to power of other primary preambles; and
a small peak-to-average ratio; and
wherein a large number of primary preamble sequences exhibit the properties; and
circuitry configured to transmit control and data channels using a variable band including a second plurality of subcarrier groups, wherein the variable band includes at least the core-band.
In its Institution Decision, the Board provided a preliminary construction of “transmit[ting] a broadcast channel in an orthogonal frequency division multiple access (OFDMA) core-band.” (Institution Decision, p. 11.) The Board stated: “the plain meaning of transmitting a broadcast channel in a core-band merely requires transmitting some part of the broadcast channel in a core-band and does not exclude transmitting another part of the broadcast channel outside the core-band.” Id.
IV disagreed with the Board’s preliminary construction, asserting that an ordinarily skilled artisan would have understood the limitation to exclude transmitting any portion of the recited broadcast channel outside of the core-band. (Patent Owner Resp., pp. 35–36.) According to the Board, Ericsson did not agree with or dispute IV’s assertion, and only asserted that IV’s proposed construction adds no clarity and that no construction is necessary.
In its Final Written Decision, the Board decided that its preliminary construction was unreasonably broad in view of IV’s arguments and its expert’s testimony:
Upon further review of the ’431 patent, particularly in view of Patent Owner’s arguments supported by Dr. Zeger’s testimony discussed above, we are persuaded that our preliminary partial construction was unreasonably broad to the extent that construction indicated the transmitting a broadcast channel limitation would be met by the transmission of a broadcast channel that is only partially within the core-band. Thus, we agree with Patent Owner that to show that the transmitting “a broadcast channel in an” OFDMA core-band limitation is met, Petitioner must demonstrate that the prior art teaches or suggests transmitting a broadcast channel, wherein the entire channel is contained within the core-band.
(Final Written Decision, pp. 8-9.) The Board determined that Ericsson’s prior art combination failed to teach transmitting a broadcast channel in an OFDMA core-band, as recited in independent claims 8 and 18. The Board found that a particular prior art reference (Yamaura) did transmit in the OFDMA core-band at times, but it did not have sufficient evidence that at other times it did not transmit outside of that band, and therefore it did not teach the recited OFDMA core-band limitation.
Even though the second IPR was instituted for trial on claims 8-12 and 18-22 based on a broad construction of the claims, the claims were not shown to be obvious based on a narrowed interpretation of the claims adopted in the Final Written Decision.