US 11,722,889 B2
Secret key generation using a relay with precoding in the null space
Magnus Stig Torsten Sandell, Bristol (GB)
Assigned to Kabushiki Kaisha Toshiba, Tokyo (JP)
Filed by Kabushiki Kaisha Toshiba, Tokyo (JP)
Filed on May 11, 2021, as Appl. No. 17/316,879.
Prior Publication US 2022/0386116 A1, Dec. 1, 2022
Int. Cl. H04W 12/041 (2021.01); H04W 12/0431 (2021.01); H04W 12/06 (2021.01); H04L 27/26 (2006.01)
CPC H04W 12/041 (2021.01) [H04L 27/2636 (2013.01); H04W 12/0431 (2021.01); H04W 12/06 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A method comprising:
transmitting, by a first communication node, a first communication via a first communication channel, an encryption key being generated in a system, the system including the first communication node, a second communication node and a relay node wherein the relay node includes a first antenna, wherein:
the first communication channel is between the first communication node and the first antenna of the relay node; and
the first communication includes a first training packet;
receiving, by the relay node, the first communication; and in response to receiving the first communication, estimating the first communication channel;
transmitting, by the second communication node, a second communication via a second communication channel wherein:
the second communication channel is between the second communication node and the first antenna of the relay node; and
the second communication includes a second training packet;
 receiving, by the relay node, the second communication; and in response to receiving the second communication, estimating the second communication channel;
 generating, by the relay node, a first transmission;
 transmitting, by the relay node, the first transmission signal via the first communication channel and the second communication channel;
 determining, by the first communication node, a first received signal from the first communication channel and the first transmission signal;
 determining, by the second communication node, a second received signal from the second communication channel and the first transmission signal;
 generating, by the first communication node, a first instance of the encryption key based on the first received signal;
 generating, by the second communication node, a second instance of the encryption key based on the second received signal, wherein:
the first transmission signal is generated based on a setting that the first received signal at an antenna of the first communication node is equal to the second received signal at an antenna of the second communication node.