Sorting Shift Register Pipeline for Faster OS-CFAR Thresholding
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Solution Overview
Problem
Existing radar systems face challenges in distinguishing between targets and clutter due to the target-masking effect and clutter edges, particularly in road environments with significant target movements, and the ordered statistic (OS)-CFAR algorithm requires numerous computations and hardware resources, leading to long processing times.
Innovation Solution
A pipeline-structured hardware device with a sorting shift register and OS-CFAR device that sorts data efficiently by using a plurality of unit blocks and a selector to determine the kth data value through minimal comparisons, reducing processing time and resource consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If simple sorting algorithms such as bubble sort are used, then the device complexity is reduced, but the productivity decreases due to M*M comparison computations
Solution Approach 1:
The sorting operation is divided into multiple pipeline stages, with each stage performing a specific comparison and swap operation. This segmentation allows the sorting process to be executed in parallel across multiple clock cycles, reducing the total number of sequential comparisons from M*M to approximately M*log(M) while maintaining manageable device complexity at each stage.
Solution Approach 2:
The sorting network uses dynamic control signals to selectively activate comparison operations based on the current state of data elements. Control logic dynamically determines which pairs of elements need comparison at each pipeline stage, optimizing the sorting process by avoiding unnecessary comparisons and adapting to the actual data distribution.
2Productivity
If fast sorting algorithms such as quick sort are used, then the productivity is improved with M log M comparison computations, but the device complexity increases
Solution Approach 1:
The quick sort algorithm is implemented using segmented pipeline stages, where each stage handles a specific level of the recursion tree. This segmentation transforms the complex recursive structure into a series of manageable iterative stages that can be implemented in hardware with controlled complexity, while maintaining the M*log(M) comparison efficiency.
Solution Approach 2:
The sorting process is transformed from a temporal recursion into a spatial pipeline structure. Instead of recursively dividing and conquering in time, the algorithm divides the sorting task across multiple parallel pipeline stages in space, achieving the same M*log(M) complexity benefit while making the hardware implementation more manageable through dimensional transformation.
3Measurement precision
If all newly incoming range data is sorted at every clock, then the measurement precision is improved, but the loss of time increases due to repeated full sorting operations
Solution Approach 1:
The sorting shift register maintains reference cells that are pre-sorted and updated incrementally as new data arrives. Instead of performing a complete sort of all incoming data at each clock cycle, the system performs preliminary sorting on the reference structure and incrementally integrates new measurements, reducing the time required while maintaining the precision needed for accurate target detection.
Solution Approach 2:
The sorting operation is made continuous through the pipeline architecture, where different stages of the sorting process operate simultaneously on different data elements. This continuous processing allows the system to maintain measurement precision by constantly updating sorted statistics while minimizing time loss through overlapping computation and data flow across pipeline stages.
4Productivity
If hardware-based parallel processing is used, then the productivity is improved by reducing processing time, but the device complexity increases due to many hardware resources required
Solution Approach 1:
The parallel processing hardware is segmented into a series of specialized pipeline stages, each performing a specific comparison and data movement function. This segmentation allows the use of simpler, more resource-efficient hardware components at each stage while achieving parallel processing throughput, reducing the overall hardware resource requirements compared to a fully parallel sorting network.
Solution Approach 2:
The pipeline register stages act as intermediaries that buffer and transfer data between processing stages. These intermediary elements enable parallel processing by decoupling the timing and data flow between stages, allowing each stage to operate independently with simpler hardware logic while maintaining the overall parallel processing capability and throughput.
Data Source
AI summary
Provided is a sorting shift register including a plurality of unit blocks connected in a pipeline structure and configured to receive a new data value and a data value to be deleted in parallel and an external comparator configured to compare the new data value and the data value to be deleted. Each of the unit blocks includes a register, a first comparator configured to compare the new data value with an internal data value of the register, a second comparator configured to compare the data value to be deleted with the internal data value, and a multiplexer configured to selectively store, in the register, one of the internal data value, the new data value, and a data value of a unit block on the left or right of the unit block in accordance with comparison results of the external comparator, the first comparator, and the second comparator.


