US 12,470,853 B2
Repeater device and transmission control techniques in quantum cryptographic communication system
Hiroshi Imai, Tokyo (JP)
Assigned to NEC CORPORATION, Tokyo (JP)
Filed by NEC Corporation, Tokyo (JP)
Filed on Jul. 28, 2023, as Appl. No. 18/227,874.
Claims priority of application No. 2022-155039 (JP), filed on Sep. 28, 2022.
Prior Publication US 2024/0107207 A1, Mar. 28, 2024
Int. Cl. H04B 10/70 (2013.01); H04L 45/02 (2022.01); H04Q 11/00 (2006.01)
CPC H04Q 11/0062 (2013.01) [H04L 45/02 (2013.01); H04Q 11/0005 (2013.01); H04Q 2011/0024 (2013.01); H04Q 2011/0073 (2013.01); H04Q 2213/13191 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A repeater device that receives signal light and reference light and transmits them in a communication network, wherein the signal light and the reference light are generated from coherent light, wherein the signal light is light of weak intensity having quantum states and the reference light is light of normal intensity having no quantum states, the repeater device comprising:
an optical route selector configured to select an input-side spatial link connected to an upstream adjacent node and an output-side spatial link connected to a downstream adjacent node;
a link state detector that detects a link state of at least one of the input-side spatial link and the output-side spatial link, wherein the link state is an attenuation rate or a transmission rate; and
a controller configured to control the optical route selector to select an optimal pair of output-side spatial link and input-side spatial link according to the link state.