A Unified Quantum–Classical Framework for BER Analysis of Different Modulations under AWGN and Fading Channels
Aahana Nischal *
Department of Electronics and Telecommunication Engineering, R. V. College of Engineering, Bengaluru, India.
Arav Jha
Department of Electronics and Telecommunication Engineering, R. V. College of Engineering, Bengaluru, India.
Nikhilesh Rao
Department of Electronics and Telecommunication Engineering, R. V. College of Engineering, Bengaluru, India.
R. Bhagya
Department of Electronics and Telecommunication Engineering, R. V. College of Engineering, Bengaluru, India.
K. Saraswathi
Department of Electronics and Telecommunication Engineering, R. V. College of Engineering, Bengaluru, India.
*Author to whom correspondence should be addressed.
Abstract
Reliable communication under additive noise, multipath fading, and mobility-induced channel variation remains a central requirement in contemporary wireless systems. This study develops a unified quantum-classical framework for examining bit error rate (BER) performance across ideal and impaired channel conditions. The classical component models orthogonal frequency-division multiplexing with BPSK, QPSK, 8-PSK, and 4-, 16-, 64-, and 128-QAM using MATLAB R2026a. The quantum-proxy component is implemented in Qiskit 2.3.0 using computational-basis qubits and Kraus-operator models for bit-flip, amplitude-damping, and phase damping noise. BER is evaluated against signal-to-noise ratio (SNR) for additive white Gaussian noise and combined fading and Doppler conditions. The classical results show a consistent reduction in BER as SNR increases, with BPSK exhibiting the greatest robustness and higher-order PSK and QAM schemes showing greater sensitivity to channel impairment. In the quantum-proxy simulation, BER remains largely independent of the number of bits represented per symbol because each qubit is encoded and measured as an independent binary state. Phase damping has negligible influence on computational-basis measurement outcomes, whereas bit-flip and amplitude-damping processes principally determine the observed errors. The numerical BER values from the two frameworks are not directly comparable because the quantum SNR axis represents a proxy mapping to noise probabilities rather than a calibrated physical Eb/N0 measure. The framework therefore supports a qualitative comparison of error mechanisms while clarifying the present limitations of basis-state quantum encoding for modelling higher-order modulation.
Keywords: Quantum communication, Qiskit, Bit Error Rate (BER), Signal-to-Noise Ratio (SNR), BPSK, QPSK, QAM, OFDM, AWGN channel, fading channels