Radio communications system
First Claim
1. A radio communications system comprising:
- a first antenna having a directivity electrically switchable;
a second antenna; and
first and second radio devices mutually transmitting and receiving a radio wave through a radio transmission path via only said first and second antennas, wherein;
said first radio device receives a radio wave or waves from said second radio device while changing a directivity of said first antenna with prescribed patterns to form a plurality of directivities, generates a first receive signal profile indicative of a signal strength of a plurality of radio waves received with the respective ones of the directivities, and generates a first private key based on the generated first receive signal profile; and
said second radio device receives a radio wave or waves from said first radio device while changing a directivity of said first antenna with prescribed patterns to form a plurality of directivities, generates a second receive signal profile indicative of a signal strength of a plurality of radio waves received with the respective ones of the directivities, and generates a second private key identical to said first private key based on the generated second receive signal profile.
1 Assignment
0 Petitions
Accused Products
Abstract
A radio communications system includes radio devices, and antenna and an array antenna. The radio devices communicate a prescribed signal via the antenna and the array antenna in a system of transmission and reception at a single frequency, such as time division duplex, as the array antenna changes the in directivity to form a plurality of directivities. The radio devices detect a plurality of received radio waves'"'"' strength to produce receive signal profiles, respectively, indicating a plurality of strength profiles. The radio devices multivalue strength of the receive signal profiles, respectively, and generate private keys having the multivalued plurality of values serving as a bit pattern.
19 Citations
12 Claims
-
1. A radio communications system comprising:
-
a first antenna having a directivity electrically switchable; a second antenna; and first and second radio devices mutually transmitting and receiving a radio wave through a radio transmission path via only said first and second antennas, wherein; said first radio device receives a radio wave or waves from said second radio device while changing a directivity of said first antenna with prescribed patterns to form a plurality of directivities, generates a first receive signal profile indicative of a signal strength of a plurality of radio waves received with the respective ones of the directivities, and generates a first private key based on the generated first receive signal profile; and said second radio device receives a radio wave or waves from said first radio device while changing a directivity of said first antenna with prescribed patterns to form a plurality of directivities, generates a second receive signal profile indicative of a signal strength of a plurality of radio waves received with the respective ones of the directivities, and generates a second private key identical to said first private key based on the generated second receive signal profile. - View Dependent Claims (2, 3, 4, 10, 11, 12)
-
-
5. A radio communications system comprising:
-
a first antenna having a directivity electrically switchable; a second antenna; and first and second radio devices mutually transmitting and receiving a radio wave through a radio transmission path via only said first and second antennas, wherein; said first radio device receives a radio wave or waves corresponding to a plurality of data transmitted by said second radio device in accordance with a prescribed communications protocol while changing a directivity of said first antenna with prescribed patterns to form a plurality of directivities, generates a first receive signal profile indicative of a signal strength of a plurality of radio waves received with the respective ones of the directivities, and generates a first private key based on the generated first receive signal profile; and said second radio device receives a radio wave or waves corresponding to a plurality of data transmitted by said first radio device in accordance with a prescribed communications protocol while changing a directivity of said first antenna with prescribed patterns to form a plurality of directivities, generates a second receive signal profile indicative of a signal strength of a plurality of radio waves received with the respective ones of the directivities, and generates a second private key identical to said first private key based on the generated second receive signal profile. - View Dependent Claims (6, 7, 8, 9)
-
Specification