SHORT-DISTANCE RADIO COMMUNICATION SYSTEM FOR VEHICLE

摘要

This short-distance radio communication system for a vehicle includes an in-vehicle unit having more than one antenna and a portable unit performing radio communications with the in-vehicle unit. The in-vehicle unit transmits a first burst together with a call signal for calling the portable unit through a first antenna, and transmits a second burst subsequent to the first burst through a second antenna. The portable unit receives the signals transmitted from the in-vehicle unit, measures respective received signal strength indicators from the first burst and the second burst contained in the received signals, and responds to the in-vehicle unit according to results of comparing the respective indicators with given thresholds.

主权项

1. A short-distance radio communication system for a vehicle, comprising:
an in-vehicle unit having a plurality of antennas; and a portable unit performing radio communications with the in-vehicle unit, wherein the in-vehicle unit has a first antenna as an in-vehicle antenna and a second antenna as an out-vehicle antenna, the in-vehicle unit transmitting a first burst together with a call signal for calling the portable unit through the first antenna, the in-vehicle unit transmitting a second burst subsequent to the first burst through the second antenna, and wherein the portable unit does not respond to the call signal to the in-vehicle unit (1) if a first received signal strength indicator measured from the first burst does not exceed a predetermined first threshold, or (2) if the first received signal strength indicator exceeds the predetermined first threshold and a second received signal strength indicator measured from the second burst exceeds a predetermined second threshold, when the portable unit receives signals transmitted from the in-vehicle unit, measures respective received signal strength indicators from the first burst and the second burst contained in the received signals, and responds to the call signal to the in-vehicle unit according to results of comparing the respective indicators with predetermined thresholds.