Abstract
In this proof-of-principle paper, the application of 2-D optical code-division multiple-access (OCDMA) modulation to long-range automotive time-of-flight (ToF) light detection and ranging (LiDAR) is studied. The regulations and physical constraints that govern the design parameters are reviewed. Using 2-D carrier-hopping prime codes (CHPCs), the modulation model and a novel 2-D hard-limiting decoder are designed and validated with OptiSystem <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\rm {TM}}$</tex-math></inline-formula> simulations. Based on the design parameters, the 2-D CHPCs have six times as many distinct sequences (for sensor identification) as 1-D code sequences. Analytical and simulation studies show that the proposed 2-D OCDMA modulation model can eliminate the near-far (power) problem and support more LiDAR sensors with distinctive ToF tags, greater interference robustness for more simultaneous ToF measurements, and better performance than the 1-D counterparts. The simulation results show that the 2-D model can support four times as many simultaneous emitting sensors without false detections as the 1-D model. In summary, the 2-D OCDMA modulation has more benefits and is more cost efficient overall, even though it is more complex.
Highlights
Light detection and ranging (LiDAR) is receiving attention in the research and development of automated vehicles because of greater benefits and capabilities, such as longrange performance, fast scanning, low cost, and superior resolution, reliability, and interference robustness, than conventional technologies using radar, ultrasound, and cameras [1], [2]
The theoretical model was validated in a LiDAR system with a single-photon avalanche diodes (SPADs) circuit that could detect multiple photons in a single measurement under high background noise power
In the proposed 2-D optical code-division multiple-access (OCDMA) modulation design, every ToF pulse is encoded into a 2-D wavelength-time sequence in the emitter of a LiDAR sensor
Summary
Light detection and ranging (LiDAR) is receiving attention in the research and development of automated vehicles because of greater benefits and capabilities, such as longrange performance, fast scanning, low cost, and superior resolution, reliability, and interference robustness, than conventional technologies using radar, ultrasound, and cameras [1], [2]. Multiple wavelengths and ideal correlation properties can enhance interference robustness and make false detections less likely than 1-D time-spreading sequences These characteristics support multiple simultaneous ToF measurements for faster scanning/frame rate and higher angular resolution [13], [14]. In the proposed 2-D OCDMA modulation design, every ToF pulse is encoded into a 2-D wavelength-time sequence in the emitter of a LiDAR sensor. The prospect of triggering unwanted nonlinearity in the APDs, which are the main opto-electrical devices in the proposed 2-D CDMA modulation model with hard-limiting, is much reduced This is because every highpower optical pulse used in the conventional pulsed-ToF measurement is split into w lower-power optical pulses in every wavelength-time sequence.
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