MIMO Radar Orthogonal Coding for Wider Unambiguous Doppler Range
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Solution Overview
Problem
Existing radar systems, particularly MIMO radar, face challenges in accurately detecting targets due to Doppler aliasing and reduced Doppler frequency ranges when using code multiplexing transmission, leading to ambiguity in Doppler frequency determination.
Innovation Solution
A radar apparatus employing code multiplexing transmission with phase-rotated orthogonal codes and unused orthogonal codes for demultiplexing, expanding the Doppler frequency range detectable without ambiguity by suppressing inter-code interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If code multiplexing transmission is used in MIMO radar, then the number of transmission signals is increased, but Doppler aliasing occurs and Doppler frequency range is reduced
Solution Approach 1:
The patent introduces orthogonal codes as intermediary elements to manage the multiplexing of transmission signals. By assigning orthogonal codes to different transmission signals, the system enables multiple signals to coexist without mutual interference, thereby increasing the number of transmissible signals while maintaining accurate Doppler frequency determination through code-based separation and identification
Solution Approach 2:
The patent changes the parameter of code length, specifically setting the code length to be larger than the code multiplexing number. This parameter change allows for sufficient code sequences to be generated for multiplexing multiple transmission signals while maintaining orthogonality and preventing Doppler aliasing, thus resolving the contradiction between signal quantity and measurement precision
2Productivity
If code multiplexing transmission is used, then transmission capacity is increased, but inter-code interference increases
Solution Approach 1:
The patent extracts and eliminates inter-code interference by using orthogonal codes with code length greater than the multiplexing number. The excess code sequences allow for complete separation of transmission signals, extracting the harmful interference component and eliminating it through orthogonal property-based signal differentiation
Solution Approach 2:
The patent converts the potential harm of inter-code interference into a benefit by utilizing the orthogonal property of code sequences. The orthogonality, which could be seen as a constraint, is transformed into a mechanism for signal separation and interference elimination, allowing multiple signals to be transmitted simultaneously without mutual disruption
Data Source
AI summary
This radar device comprises a signal generation circuit for generating a baseband signal, a code generation circuit for generating a plurality of code sequences, a phase rotation circuit for applying phase rotation based on one of the code sequences from among the plurality of code sequences to the baseband signal and generating a plurality of code multiplexed transmission signals, and a plurality of transmission antennas for transmitting the plurality of transmission signals. The code length of the plurality of code sequences is greater than the code multiplexing number of the plurality of transmission signals.