Orthogonal Signal Generation for CDMA MIMO Radar
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Solution Overview
Problem
CDMA MIMO radar systems face interference due to orthogonality imperfections, leading to cross-correlation issues that reduce detection range and radar performance.
Innovation Solution
A method to generate a family of orthogonal signals using an algorithm that selects candidate signals based on cross-correlation values, adjusting a parameter value α to change the curvature of signals, and deriving factors w, k1, and k2 to determine instantaneous frequency and phase, thereby reducing cross-correlation by iteratively identifying signals with minimal cross-correlation sums and maximum values below a threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple transmitters transmit different codes simultaneously in a CDMA MIMO radar system, then the detection capability and tracking performance are improved, but cross-correlation interference occurs due to orthogonality imperfections
Solution Approach 1:
The patent applies parameter changes by modifying the signal waveform parameters (curvature parameter α, bandwidth B, duration T) to generate orthogonal signals with different instantaneous frequency characteristics. By deriving factors w, k1, and k2 from these parameters and adjusting the phase and frequency modulation, the system creates signals that maintain orthogonality while enabling simultaneous transmission from multiple transmitters, thus improving detection capability without cross-correlation interference
Solution Approach 2:
The patent implements preliminary action by pre-selecting and storing a family of orthogonal signals with known cross-correlation properties before radar operation. The system预先 generates and stores multiple signal waveforms with optimized parameters, then selects appropriate signals from this pre-prepared family for transmission, ensuring orthogonality is maintained from the outset rather than attempting to correct interference during operation
2Productivity
If traditional orthogonal signals are used in CDMA MIMO radar, then simultaneous transmission from multiple transmitters is enabled, but side lobe levels increase reducing signal quality
Solution Approach 1:
The patent reduces side lobe levels by optimizing signal parameters including bandwidth B, duration T, and curvature parameter α. By deriving factors w, k1, and k2 from these parameters and adjusting the phase modulation function φ(t) and instantaneous frequency f(t), the system generates signals with suppressed side lobes that maintain orthogonality while improving signal quality for simultaneous multi-transmitter operation
Data Source
AI summary
A system and method to generate a family of orthogonal signals for a code division multiple access (CDMA) radar system involve selecting a first signal of the family of orthogonal signals for transmission by one of a plurality of transmitters of the radar system. The method includes using an algorithm to determine a second signal of the family of orthogonal signals. The algorithm uses cross-correlation values between candidate signals for consideration as the second signal of the family of orthogonal signals and the first signal. The method also includes transmitting the first signal of the family of orthogonal signals and the second signal of the family of orthogonal signals simultaneously from two different transmitters, and obtaining and processing reflections resulting from transmission of the first signal of the family of orthogonal signals and the second signal of the family of orthogonal signals.