Hybrid Optical Phased Array Alignment Using RF Angle of Arrival
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Solution Overview
Problem
Existing free-space optical (FSO) and radio-frequency (RF) communication systems face challenges in alignment and efficiency, particularly in inter-satellite communication, with FSO requiring precise aiming and RF systems consuming more power and offering less bandwidth.
Innovation Solution
A hybrid optical-RF communication system using RF antenna units to determine the angle of arrival (AOA) for FSO alignment, enabling iterative alignment adjustments through RF signaling, combining RF links with optical signal transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If free-space optical communication is used to provide fast communication, then communication speed is improved, but alignment difficulty increases when transmitter and receiver are moving relative to one another
Solution Approach 1:
The patent introduces RF signals as an intermediary to facilitate alignment between optical transmitters and receivers. The RF signals have larger divergence and can more easily locate the receiver, providing guidance for aligning the precise optical link without requiring the optical system to perform complex sweeping operations.
Solution Approach 2:
The system performs preliminary alignment using RF signals before establishing the optical communication link. By first using RF to determine the angle of arrival and pre-align the optical beam, the system avoids the need for time-consuming optical sweeping and scanning operations during actual data transmission.
2Reliability
If FSO transmitter sweeps or scans space to locate receiver, then alignment is achieved, but time and power are consumed
Solution Approach 1:
RF signals serve as a mediator that enables rapid location of the receiver through their larger divergence pattern. The optical transmitter uses these RF signals to determine the angle of arrival and directly aim the optical beam, eliminating the need for slow optical sweeping and scanning operations.
Solution Approach 2:
The patent replaces the mechanical sweeping and scanning operations with an electronic beam steering approach guided by RF signals. Instead of physically moving or scanning the optical beam across space, the system uses RF-derived angle information to electronically direct the optical beam toward the receiver.
3Reliability
If FSO transmitter sweeps or scans space to locate receiver, then alignment is achieved, but power is consumed
Solution Approach 1:
RF signals act as a low-power intermediary that provides directional information to the optical transmitter. By using RF to determine the angle of arrival, the optical system can directly aim its beam without consuming excessive power on sweeping and scanning operations, significantly reducing the overall power requirement for alignment.
4Ease of operation
If RF phased array systems are used to provide easier alignment, then alignment ease is improved, but communication power increases and bandwidth decreases
Solution Approach 1:
The system uses RF signals only for preliminary alignment purposes to determine the angle of arrival, then switches to optical communication for actual data transmission. This hybrid approach captures the alignment ease of RF systems while avoiding their high power consumption and limited bandwidth during the primary communication phase.
Solution Approach 2:
The communication system is segmented into two functional parts: RF for alignment and localization, and optical for high-speed data transmission. This segmentation allows each subsystem to operate in its optimal performance regime, with RF handling the alignment task and optical handling the bandwidth-intensive communication task.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Facilitates time- and power-efficient alignment of FSO systems, providing fast and directional communication links between moving electronic devices.
Implementation Method 1
receiving, by a radio frequency (RF) antenna unit of a first electronic device (FED), a RF signal from a second electronic device (SED), with the RF signal having associated thereto an angle of arrival (AOA) at the FED
Implementation Method 2
transmitting, by the light source, an optical signal towards the SED, the optical signal encoding a data message
Data Source
AI summary
Methods and systems for communicating messages through free space are provided. In particular, examples or implementations facilitate communication between moving devices separated by free space. In examples or implementations, a radio-frequency (RF) communication link is first established between the devices. When one device intends to transmit data to another device, the one device, using an RF phased array, determines an angle-of-arrival for RF signals received from the other device. The one device then aims a light source according to the determined angle-of-arrival and transmits the data as an optical signal. In some examples or implementations, the other device at least partly receives, using a light detector, the optical signal and determines an alignment offset from the light detector. The other device then communicates the alignment offset to the one device by a further RF signal so that the alignment can be improved.