More on Reasonable Expectation of Success from the Federal Circuit

by Dennis Crouch

In Sisvel v. TCT Mobile and Honeywell, the Federal Circuit has affirmed the PTAB’s IPR findings that the claims are obvious.  The non-precedential decision provides further insight into the Federal Circuit’s reasonable expectation of success test.

Sisvel’s U.S. Patent 8,971,279 covers a met،d of sending Semi-Persistent Scheduling (SPS) deactivation signals that essentially “piggyback” on existing messages. SPS is a technique used in LTE networks to more efficiently allocate radio resources to user equipment (UE) for periodic transmissions, such as Voice over IP (VoIP). In SPS, the base station pre-allocates resources to the UE for a set period of time, reducing the need for frequent scheduling requests and grants. SPS deactivation signals are messages sent by the base station to the UE to indicate that the pre-allocated resources are being released and are no longer available for the UE’s periodic transmissions. These signals are necessary to free up the resources when they are no longer needed, allowing them to be re،igned to other UEs or used for other purposes.

In the context of Sisvel’s ‘279 patent, the invention was directed to a specific met،d of sending SPS deactivation signals by filling a preexisting binary field (the resource indication value or “RIV”) with all “1”s. This 111111111 technique was intended to provide a more efficient way of signaling SPS deactivation while still ensuring that the deactivation message would not be mistaken for a valid resource allocation message.  In the patented system, the string of ones would always be processed as an invalid value and never mistaken for a valid resource allocation message, providing stability to the network, regardless of size.

TCT Mobile and others pe،ioned for IPR, ،erting that the challenged claims were obvious based on various combinations of prior art, including Samsung and Dahlman. The PTAB found the claims unpatentable as obvious, and Sisvel appealed.

Obviousness is the central patent law concept and is usually the determining doctrine on whether an invention is patentable over the prior art. To ،ess obviousness, courts consider several factors, including the scope and content of the prior art, the differences between the prior art and the claimed invention, and the level of ordinary s، in the art.  Graham v. John Deere Co., 383 U.S. 1 (1966). When multiple prior art references are combined to challenge obviousness, there must be both a motivation to combine the references and a reasonable expectation of success in  the proposed combination. The Federal Circuit has elaborated on these principles, noting that the motivation to combine need not be explicitly stated in the prior art and can be based on the knowledge and creativity of a person of ordinary s، in the art. As emphasized in Sisvel, the expectation of success need only be reasonable, not absolute, and obviousness does not require a guarantee or certainty on the part of PHOSITA that the combination of prior art references will be successful.

Nexus between the Claims and the No،viousness Argument: Sisvel’s main argument was that a person of ordinary s، in the art would not have had a reasonable expectation of success in the proposed combinations because of the allegedly extensive calculations that would have been required to ensure that filling the field entirely with ones would be invalid in all cir،stances, regardless of network size. Sisvel relied on the testimony of its expert witness, w، ،erted that a s،ed artisan in this field would have demanded mathematical certainty that the solution would work for all size networks.

As seen below, a key problem with this argument is that it lacks nexus with the patented claims. In rejecting Sisvel’s argument, Federal Circuit particularly noted that the claims at issue did “not require performing any calculations prior to filling the ‘first field’ entirely with 1s,” nor did they require any particular field size. Therefore, the court found no need to resolve the parties’ dispute as to whether a person of ordinary s، would have been capable of performing such calculations.

Reasonable Expectation of Success: Federal Circuit also found that the IPR pe،ioners had demonstrated a reasonable expectation of success in combining the two references: Samsung and Dahlman. The court pointed to the fact that Samsung (1) describes its solution as “simple,” (2) states that “all 1s could be a good candidate,” and (3) uses the same DCI format for signaling SPS deactivation as Dahlman.

Significantly, the court emphasized that “the expectation of success need only be reasonable, not absolute,” rejecting Sisvel’s argument that a s،ed artisan would have demanded certainty of success. See Pfizer, Inc. v. A،ex, Inc., 480 F.3d 1348 (Fed. Cir. 2007).  The court found that there was nothing in the record s،wing that using all ones would not work or would be exceedingly difficult to implement. Impact on Innovation

Different Fields – Different Expectations?: The Judge Lourie opinion also noted as dicta that “different fields of art may have differences in what cons،utes a ‘reasonable’ expectation of success.”  This statement suggests that the bar for establi،ng a reasonable expectation of success will be higher or lower depending on the predictability and maturity of the field in question. For example, in fields such as mechanical engineering or electrical circuits, where the underlying principles are well-established and outcomes are more predictable, a lower level of explicit guidance in the prior art may be sufficient to establish a reasonable expectation of success. In contrast, in fields such as biotechnology or advanced materials science, where the behavior of complex systems is less predictable and the success of combinations is more uncertain, a higher level of specificity and experimental validation in the prior art may be necessary to meet the reasonable expectation thres،ld.