US-12627375-B2 - Optical frontend for use in optical wireless communication

US12627375B2US 12627375 B2US12627375 B2US 12627375B2US-12627375-B2

Abstract

The invention relates to an Optical Front-end, OFE, ( 400 ) for Optical Wireless Communication, OWC, the OFE comprising: an optical receiver with at least a photodetector ( 102 a ) and a trans-impedance amplifier, and a two-dimensional array of optical transmitters ( 103 a ) each having an individual transmitter field-of-view, and one or more drivers, the two-dimensional array arranged to create a combined transmitter field of view that is larger than 5 the individual transmitter field of view, the plurality of optical transmitters arranged such that optical axes of the plurality of optical transmitters are evenly distributed within the combined transmitter field of view.

Inventors

FRANCISCO DAVID ROJAS CALVENTE
Paul Henricus Johannes Maria Van Voorthuisen

Assignees

SIGNIFY HOLDING B.V.

Dates

Publication Date: 20260512
Application Date: 20220422
Priority Date: 20210429

Claims (9)

1 . An Optical Front-end (OFE) for Optical Wireless Communication (OWC) the OFE comprising: an optical receiver with at least one photodetector, the at least one photodetector facing in a detection direction, and a Trans-Impedance Amplifier (TIA) for amplifying the signal from the at least one photodetector, and a two-dimensional array of optical transmitters each having an individual transmitter field-of-view, and corresponding drivers, the two-dimensional array of optical transmitters arranged to create a combined transmitter field of view that is larger than the individual transmitter field of view, and where the number of optical transmitters along a first direction is larger than the number of optical transmitters along a second direction and the combined transmitter field of view in the first direction is larger than in the second direction, the first direction orthogonal to the second direction, the optical transmitters arranged such that optical axes of the optical transmitters are evenly distributed within the combined transmitter field of view, wherein the optical receiver is mounted on a flat substrate with its optical axis aligned with the optical axis of the combined transmitter field of view and the receiver field of view is larger than, or equal to, the combined transmitter field of view and wherein the optical transmitters are either: positioned along a surface that is curved around a first axis and curved around a second axis, the first and second axis orthogonal to one another, the first axis perpendicular to the first direction, the second axis perpendicular to the second direction; positioned with at least one point on a flat surface, each optical transmitter angled to face in a different direction; or positioned on a flat surface and are fitted with a respective optical wave-guide for directional outcoupling.
2 . The OFE of claim 1 , wherein the array of optical transmitters are arranged in a matrix along two orthogonal directions or in a hexagonal structure.
3 . The OFE of claim 1 , wherein the combined transmitter field of view in the first direction is within a range of 30 degrees to 90 degrees and in the second direction is within a range of 10 to 60 degrees.
4 . An OWC transceiver system for optical wireless communication (OWC) for use with a further OWC transceiver system, the OWC transceiver system comprising: the Optical Front-End (OFE) as claimed in claim 1 , wherein the OFE includes a separate driver for each of the plurality of optical transmitters, a baseband unit configured to modulate outgoing data for transmission by the OFE and to demodulate incoming data from the output of the transimpedance amplifier of the OFE, and a controller configured, to control which of the plurality of optical transmitters are used for transmitting the outgoing data, based on the outcome of an alignment operation.
5 . The OWC transceiver of claim 4 , wherein the controller is arranged to perform an alignment operation with the further OWC transceiver system, wherein the controller is configured to: generate unique orientation beacons comprising identifying information for each one of the plurality of optical transmitters; control each of the plurality of transmitters to transmit their respective orientation beacon; receive, in the output of the TIA, feedback transmitted by the communication partner on a detection from a communication partner on a unique attribute of an optical transmitter of the OWC transceiver system in a beacon from the OWC transceiver system; and select a proper subset from the plurality of optical transmitters for transmitting the outgoing data to the further OWC transceiver system based on the feedback.
6 . The OWC transceiver of claim 5 , wherein the orientation beacons are low frequency, CDMA beacons that are transmitted out-of-band from the output data, thereby allowing optical transmitters to transmit orientation beacons and output data simultaneously; and wherein the feedback on the detection from the communication partner, is a beacon transmitted by the communication partner with an inverted version of the CDMA sequence as was transmitted by a respective one of the optical transmitters received by the communication partner.
7 . A vehicle arranged for optical communication, the vehicle comprising: an in-vehicle network, a first OWC transceiver comprising a forward facing OFE as claimed in claim 1 , the forward facing OFE's optical axis facing in the forward-facing motion direction of the vehicle, wherein the in-vehicle network is connected to the first OWC transceiver.
8 . The vehicle of claim 7 , the vehicle further comprising: a second OWC transceiver comprising a backward facing OFE, the backward-facing OFE's optical axis facing opposite to the forward-facing motion direction of the vehicle, wherein the in-vehicle network is connected to the second OWC transceiver.
9 . The vehicle of claim 7 , wherein the vehicle is one of a car, bus, train, boat, or truck.

Description

CROSS-REFERENCE TO PRIOR APPLICATIONS This application is the U.S. National Phase application under 35 U.S.C. § 371 of International Application No. PCT/EP2022/060746, filed on Apr. 22, 2022, which claims the benefit of European Patent application Ser. No. 21/171,082.7, filed on Apr. 29, 2021, and European Patent Application No. 21212679.1, filed on Dec. 7, 2021. These applications are hereby incorporated by reference herein. FIELD OF THE INVENTION The invention relates to the field of Optical Front-ends for Optical Wireless Communication (OWC), which may find use in an OWC transceiver system, which may be deployed for example in vehicle-to-vehicle (V2V) networks or vehicle-to-infrastructure (V2I) networks. BACKGROUND OF THE INVENTION Optical wireless communication enables mobile devices to connect wirelessly to one another using optical communication. In contrast to radio frequency communication OWC achieves this using the light spectrum which can enable unprecedented data transfer speed and bandwidth. Furthermore, it can be used in areas susceptible to electromagnetic interference and on account of the directional nature of light-based communication, is based on line-of-sight links. Optical communications may make use of either the visible or infrared spectrum. The advantage of using the infrared spectrum is that it is not immediately perceptible by humans. In contrast visible light when integrated in functional light may not be bothersome, but when used in horizontal communication, as for example when used between vehicles during the daytime, may be perceived as bothersome. In that case, use of infrared may be preferable. Based on modulation data can be embedded in the light output and information in the optical communication signals can be detected using any suitable light sensor and corresponding demodulator. Photodetectors may be a dedicated photocell (point detector), or an array of photocells such as a camera. Data may be modulated using a variety of modulation techniques ranging from simple Pulse Amplitude Modulation to Orthogonal Frequency Division Multiplex modulation. The latter has lately received considerable attention and various techniques may be used to address the fact that light in contrast to electrical signals requires a unipolar modulation. As a result, techniques such as ACO-OFDM and Flip OFDM have been devised in order to avoid having to add an offset to the light output. Achieving a high data throughput and/or long range in a point-to-point OWC system, while maintaining a wide-angle coverage, is a challenge. This is not only because of the increased power requirements for the transmitter, but also because increasing the transmission power in optical systems above certain level is not always possible due to eye-safety requirements. To address this problem, it is known to deploy electro-mechanical systems that are used to perform beam-steering. In such systems the output beam direction is adapted, under automated motor control. Know alternatives, instead use mechanical actuators in combination with mirrors for beam-steering. However, systems that use mechanical parts are expensive and prone to have reliability issues, especially in some common use cases of beam steering systems such as vehicle-to-vehicle communication. SUMMARY OF THE INVENTION The present invention proposes an alternative way to mechanical beam-steering, that does not use moving mechanical or electro-mechanical parts, and instead uses multiple narrow angle transmitters and a wide-angle receiver to perform beam selection. In accordance with a first aspect of the invention, an Optical Front-end, OFE, is provided for Optical Wireless Communication, OWC, the OFE comprising: an optical receiver with at least a photodetector, the at least one photodetector facing in a detection direction, and a Trans-Impedance Amplifier, TIA, for amplifying the signal from the at least one photodetector, and a two-dimensional array of optical transmitters each having an individual transmitter field-of-view, and corresponding drivers, the two-dimensional array arranged to create a combined transmitter field of view that is larger than the individual transmitter field of view, and where the number of optical transmitters along a first direction is larger than the number of optical transmitters along a second direction and the combined transmitter field of view in the first direction is larger than in the second direction, the first direction orthogonal to the second direction, the optical transmitters arranged such that optical axes of the optical transmitters are evenly distributed within the combined transmitter field of view, wherein the optical transmitters are either: (1) positioned along a surface that is curved around a first axis and curved around a second axis, the first and second axis orthogonal to one another, the first axis perpendicular to the first direction, the second axis perpendicular to the second direction; (2) positioned