This paper proposes an adaptive wavelet division multiplexing scheme for wireless systems serving users with heterogeneous mobility profiles over frequency-selective Rayleigh fading channels. By exploiting the multiresolution structure of the discrete wavelet transform (DWT), users are adaptively assigned to different decomposition levels according to their channel dynamics and Doppler conditions. A single-tap minimum mean square error (MMSE) equalizer is applied in the frequency domain, and the system performance is evaluated under realistic time-varying multipath fading environments. Simulation results demonstrate that the proposed adaptive allocation achieves balanced bit error rate (BER) across all user mobility classes while delivering substantial peak-to-average power ratio (PAPR) reductions relative to both conventional orthogonal frequency division multiplexing (OFDM) and orthogonal time-frequency space (OTFS) modulation. The proposed framework is further validated in a four-user heterogeneous-mobility scenario, confirming its scalability and effectiveness to mixed-mobility multi-user scenarios.
This paper presents a novel intelligent chaotic-based code-division multiple access (CDMA) scheme for underwater optical wireless communication (UOWC), addressing critical performance degradation caused by severe scattering and multipath dispersion in underwater environments. Unl…
In future 6G vehicular networks, users employing orthogonal frequency division multiplexing (OFDM) and orthogonal time frequency space (OTFS) waveforms may coexist under diverse mobility conditions, where both can experience high-mobility and low-mobility profiles. Since OFDM use…
This paper proposes an affine frequency division multiplexing (AFDM)-aided faster-than-Nyquist (FTN) waveform, termed AFDM-FTN, to enhance spectral efficiency (SE) in high-mobility communication scenarios. We first derive the AFDM-FTN input-output relationship and analyze the FTN…
We propose a novel doubly-dispersive (DD) multiple-input multiple-output (MIMO) channel model incorporating flexible intelligent metasurfaces (FIMs), suitable for integrated sensing and communications (ISAC) in high-mobility scenarios. We show how the proposed FIM-parameterized D…
Zak-Orthogonal Time Frequency Space (OTFS) modulation is known to be robust to Doppler spread in high mobility scenarios when compared to Orthogonal Frequency Division Multiplexing (OFDM). This is due to the fact that the channel response to a Zak-OTFS carrier within a frame can…
This paper presents a Multi-Map Dynamic-Entropy Intrusion-Aware Chaotic Modulation (MU-DE-IAEACM-MM) framework for adaptive physical-layer security in multi-user wireless systems. Unlike conventional chaos-based schemes that rely on static parameter secrecy, the proposed architec…