Patent 9396597 was granted and assigned to Honda on July, 2016 by the United States Patent and Trademark Office.
Upon determination that a mobile device is present within a first communication area, a control device maintains transmitter power output of an electromagnetic wave to be transmitted from a communication section. Further, the mobile device decreases sensitivity for receiving the electromagnetic wave such that the first communication area is narrowed to a second communication area. Then, the control device determines, based on presence/absence of a response from the mobile device, whether the mobile device is present within the second communication area.