US 12,132,517 B2
Optimizing alignment in optical communication
Willem Arjan Klop, Bruchem (NL); Remco Den Breeje, Papendrecht (NL); Rudolf Saathof, Nieuwegein (NL); and Nicolaas Jan Doelman, Burgh-Haamstede (NL)
Assigned to Nederlandse Organisatie voor toegepast-natuurwetenschappelijk onderzoek TNO, 's-Gravenhage (NL)
Appl. No. 17/767,828
Filed by Nederlandse Organisatie voor toegepast-natuurwetenschappelijk onderzoek TNO, 's-Gravenhage (NL)
PCT Filed Oct. 9, 2020, PCT No. PCT/NL2020/050623
§ 371(c)(1), (2) Date Apr. 8, 2022,
PCT Pub. No. WO2021/071359, PCT Pub. Date Apr. 15, 2021.
Claims priority of application No. 19202674 (EP), filed on Oct. 11, 2019.
Prior Publication US 2024/0088998 A1, Mar. 14, 2024
Int. Cl. H04B 10/11 (2013.01); H04B 10/112 (2013.01)
CPC H04B 10/1123 (2013.01) 20 Claims
OG exemplary drawing
 
1. A method for maintaining a point ahead angle between an uplink beam from a first terminal to a second terminal, and a downlink beam from the second terminal to the first terminal, the method comprising:
providing a communication link for optical communication between the first terminal and the second terminal, wherein the communication link comprises:
a reception channel through which the first terminal receives data via the downlink beam from the second terminal, and
a transmission channel through which the first terminal transmits data via the uplink beam to the second terminal along an initial point ahead angle with respect to the downlink beam;
applying, while transmitting data via the transmission channel from the first terminal to the second terminal, a directional variation to the initial point ahead angle for emitting the uplink beam along different point ahead angles at different instances of time;
determining, at the second terminal, a respective intensity of a part of the uplink beam received by the second terminal that is emitted by the first terminal along a respective point ahead angle;
communicating an indication of the respective intensity, determined by the second terminal, to the first terminal via the reception channel and/or communicating an indication of the respective point ahead angle, used by the first terminal in emitting the uplink beam, to the second terminal via the transmission channel; and
adjusting, in the first terminal, the initial point ahead angle towards a point ahead angle based on the respective intensity, determined in the second terminal, as a function of the different point ahead angles at which the uplink beam was emitted by the first terminal,
wherein the emitting the uplink beam along the different point ahead angles comprises:
emitting, by the first terminal, the uplink beam as a first beam along a first point ahead angle with respect to the downlink beam;
determining, by the second terminal, a first intensity of a part of the first beam received by the second terminal;
emitting, by the first terminal, the uplink beam as a second beam along a second point ahead angle with respect to the downlink beam, wherein the second point ahead angle is different from the first point ahead angle;
determining, by the second terminal, a second intensity of a part of the second beam received by the second terminal; and
adjusting, by the first terminal, the initial point ahead angle based on a difference between the first intensity and second intensity.