LIDAR Raw Data Delta Encoding for Bandwidth-Limited Transfer
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Solution Overview
Problem
Current LIDAR systems face challenges in compressing raw data efficiently, particularly in the automotive LiDAR sensor context, where data rates reach several Gbit/s, and existing compression techniques primarily focus on 3D point clouds without addressing data capture and transfer from sensors to computing units.
Innovation Solution
A LIDAR system with a photodetector array, multibit analog-to-digital converters (ADCs), and an encoder that generates compressed data packets by converting electrical signals into ADC data samples and applying delta encoding with thresholding and averaging techniques to reduce data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If conventional LIDAR data compression techniques are used, then data transmission bandwidth is reduced, but compression is applied only to 3D point clouds and not to raw sensor data
Solution Approach 1:
The patent segments the LIDAR data processing pipeline into distinct stages: raw data acquisition, ADC conversion, delta encoding, and compression. By applying compression at the raw data stage before full processing, it enables versatility across different data formats and processing stages, not just final 3D point clouds.
Solution Approach 2:
The patent performs preliminary compression actions on raw LIDAR data immediately after ADC conversion, before the data undergoes full processing pipelines. This preliminary encoding reduces the data volume early in the workflow, benefiting subsequent processing stages and reducing overall transmission requirements.
2Measurement precision
If high data rates are transmitted from LIDAR sensors, then measurement quality is maintained, but data transmission bandwidth requirements increase to several Gbit/s
Solution Approach 1:
The patent changes the parameter representation of LIDAR data by applying delta encoding, which transforms absolute distance values into differential changes. This parameter transformation maintains measurement precision while significantly reducing the bandwidth required for transmission, as small changes require fewer bits to represent.
Solution Approach 2:
Instead of transmitting full-precision raw data, the patent transmits a compressed representation that captures the essential measurement information. The delta-encoded data serves as an efficient copy that preserves measurement quality while reducing transmission bandwidth requirements.
3Loss of substance
If delta encoding is applied to LIDAR data, then data compression ratio increases, but handling of large delta values requires full bitwidth allocation
Solution Approach 1:
The patent applies partial delta encoding by using reduced bitwidth for most data points where small deltas are expected, while allocating full bitwidth only when necessary for large delta values. This partial application of full precision maintains compression efficiency while handling edge cases appropriately.
Solution Approach 2:
The patent implements dynamic bitwidth allocation where the number of bits used to represent delta values changes based on the magnitude of the delta. Small deltas use fewer bits, while large deltas automatically receive more bits, creating a flexible system that adapts to the actual data characteristics rather than using a fixed bitwidth.
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
The proposed solution achieves a data compression ratio of up to 33-34%, enabling efficient full-waveform transfer and reducing data traffic between the receiver circuit and system controller, while maintaining a lossless compression mode independent of signal-to-noise ratio (SNR).
Implementation Method 1
a photodetector array configured to generate a plurality of electrical signals based on receiving a reflected light beam
Data Source
AI summary
A Light Detection and Ranging (LIDAR) receiver includes a photodetector array configured to generate a plurality of electrical signals; a receiver circuit including a plurality of readout channels, configured to read out the plurality of electrical signals from the photodetector array, and a plurality of multibit ADCs, wherein each of the plurality of readout channels includes a different one of the plurality of multibit ADCs, and each of the plurality of multibit ADCs is configured to convert at least one of the plurality of electrical signals into an ADC data sample such that the plurality of multibit ADCs generate a sequence of ADC data samples; an encoder coupled to the plurality of readout channels and configured to receive the sequence of ADC data samples and generate a compressed data packet based on the sequence of ADC data samples; and a communication interface configured to transmit the compressed data packet.