under consideration in this case is US patent 6,018,642, owned by Fujitsu. The patent under consideration claimed "a system for reducing power consumption in mobile devices that access wireless networks". In the 642 patent, to save the energy consumption, the mobile station's wireless communication subsystem is configured to only power up in time to receive the beacon signals noticing that there is data to transfer and if no data is available, immediately power off. The idea behind this patent is to keep the wireless radio in a low-power state as much as possible to preserve energy. Meaning of "Synchronous" There were especially two terms used in claims in the 642 patents that required clarification. In both the district and circuit court, potential infringement centered on the definition of "synchronous". In Fujitsu's patent, the function of the alert beacon signal is described as "an intermittent power-on type mobile station for shift to a power-on state synchronously with a received timing of a beacon signal, with a fixed period of time after the beacon signal has been received being defined as a data receive-ready period". The district court construed the phrase "shifting to a power on state synchronously with a received timing of a beacon signal" to mean "shifting to a power-on state at the same time a beacon signal is to be received. Meaning of "Fixed period of time" for Data Receive-Ready (DRR) period Also, one of the claim in the 642 patent described that data receive-ready(DRR) period is " a fixed period of time during which an intermittent power-on type mobile station is in its power on state and prepared to receive data, with the period beginning immediately after the intermittent power-on type mobile station receives the beacon signal telling it there is data to be transmitted to it". The issue here was what exactly the fixed period of time means. The court held that the DRR period must have a fixed length for the Netgear's devices to infringe the 642 patent. Patent infringement analysis by the district court The district court stated that the jury could not find that the device literally infringed the "synchrnously" element of the 642 patent, because it was impossible to know from plaintiffs' oscilloscope graphs (one of the evidence submitted by plaintiff) the precise time between when defendant's accused mobile devices reach their power-on mode and when a beacon signal is to be received.