Infringement search: communication device patents
This example is about a Japanese prior art search to invalidate a target US patent about adjustment of time and frequency domain equalizers in a communications device, an infrigement litigation case.
Japanese documents published before 2004
NRI, Patolis, and JPO/IPDL combination
Patent infringement litigation case
In this project, we used full text, classification, cross-reference, and combination of these search approaches to cover a wide scope. These Japanese patent searches generated 589+ hits.
Search strings used and number of hits generated are summarized below for reference.
Search strings used:
(“equalizer” OR “equalization”) AND “frequency domain” AND “time domain” AND (H04B1/+ H03H7/+ H01Q21/+ H04Q7/+ H04B7/+ H04L12/)
After screening and reviewing full documents of these hits, we uncovered 7 Japanese documents that are considered to be relevant art. One of the patent found discloses a training method of a time domain equalizer and digital data transmission apparatus comprising a time domain equalizer and frequency domain equalizer. Tap-coefficient is updated so that an error between the tap coefficients and channel target characteristic becomes zero.