US 12,040,831 B2
Optical communication system and master station
Hirotaka Ujikawa, Musashino (JP); Rintaro Harada, Musashino (JP); and Shin Kaneko, Musashino (JP)
Assigned to NIPPON TELEGRAPH AND TELEPHONE CORPORATION, Tokyo (JP)
Appl. No. 17/917,597
Filed by NIPPON TELEGRAPH AND TELEPHONE CORPORATION, Tokyo (JP)
PCT Filed Apr. 14, 2020, PCT No. PCT/JP2020/016476
§ 371(c)(1), (2) Date Oct. 7, 2022,
PCT Pub. No. WO2021/210078, PCT Pub. Date Oct. 21, 2021.
Prior Publication US 2023/0142562 A1, May 11, 2023
Int. Cl. H04B 10/03 (2013.01); H04B 10/032 (2013.01); H04B 10/275 (2013.01); H04L 43/0864 (2022.01); H04J 14/02 (2006.01); H04Q 11/00 (2006.01)
CPC H04B 10/032 (2013.01) [H04B 10/2755 (2013.01); H04L 43/0864 (2013.01); H04B 10/03 (2013.01); H04B 10/275 (2013.01); H04J 14/0287 (2013.01); H04Q 11/0062 (2013.01); H04Q 11/0067 (2013.01); H04Q 2011/0079 (2013.01); H04Q 2011/0081 (2013.01); H04Q 2011/0092 (2013.01)] 8 Claims
OG exemplary drawing
 
1. An optical communication system comprising:
a plurality of slave station devices that are connected to a loop path in parallel; and
a master station device that is connected to the loop path and configured to perform communication with each of the slave station devices,
wherein communication paths between the master station device and each of the slave station devices include:
a normal path that extends along the loop path from the master station device to each of the slave station devices in a first direction, and
a backup path that extends along the loop path from the master station device to each of the slave station devices in a second direction that is opposite to the first direction,
the master station device is configured to execute:
ranging processing for setting a QuietWindow and measuring an RTT (Round Trip Time) between the master station device and each of the slave station devices, and
communication control processing for controlling communication with the slave station devices based on the RTTs,
a normal path RTT is the RTT in a case of communication performed via the normal path,
a backup path RTT is the RTT in a case of communication performed via the backup path,
a disconnected slave station device is a slave station device that cannot perform communication via the normal path, among the plurality of slave station devices,
if the disconnected slave station device does not exist, the master station device executes the communication control processing with respect to the slave station devices based on the normal path RTTs,
if the disconnected slave station device is detected, the master station device executes the ranging processing and measures the backup path RTT for the disconnected slave station device, and resumes the communication control processing with respect to the disconnected slave station device based on the backup path RTT,
a first slave station device is a disconnected slave station device having a first normal path RTT as the normal path RTT,
a second slave station device is a disconnected slave station device having a second normal path RTT as the normal path RTT, the second normal path RTT being longer than the first normal path RTT,
a first backup path RTT is the backup path RTT between the master station device and the first slave station device,
a second backup path RTT is the backup path RTT between the master station device and the second slave station device, and
in the ranging processing for measuring the backup path RTT, based on a fact that the first backup path RTT is longer than the second backup path RTT, and that the second backup path RTT is shorter than the first backup path RTT, the master station device limits the QuietWindow to a size smaller than a predetermined maximum size.