Reserved-subcarrier GA waveform design for MIMO-OFDM energy-constrained sensor systems
This paper studies waveform design for energy-constrained multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) sensor systems. The central issue is that waveform peaks affect the two ends of the link in different ways. At the transmitter, a low peak-to-average power ratio (PAPR) is desirable because it improves power-amplifier (PA) efficiency and mitigates nonlinear distortion. At the receiver, however, sufficiently strong instantaneous peaks can be beneficial for rectification, wake-up support, and intermittent low-power sensor activation. Motivated by this dual requirement, we develop a PAPR-aware waveform design method that jointly considers transmit-side PAPR and receive-side peak characteristics. A subset of subcarriers is reserved for waveform shaping, and a real-coded genetic algorithm (GA) is used to optimize the corresponding frequency-domain variables under a transmit-side PAPR constraint and a total-power normalization condition. Simulation results show that, compared with a channel-matched MRT benchmark, the proposed method reduces transmit-side PAPR while enhancing receive-side peak behavior and rectification efficiency. These results demonstrate that peak-aware physical-layer waveform design can provide a useful trade off between transmission efficiency and sensor-side energy support in energy-constrained sensor systems.