arXiv subjects

Daniel C. Araújo

Publications and source records attributed to Daniel C. Araújo.

4 recordsLinked to original sources

arXiv2026

Receive Diversity for Differential Binary Noise Modulation

Differential binary noise (DBN) modulation encodes information in the polarity transition of a reused noise realization, dispensing channel state information and carrier-phase recovery. This letter proposes single-input multiple-output (SIMO) reception for DBN via post-correlation decision-statistic combining, followed by one zero-threshold decision. The combined statistic is a Hermitian quadratic form in complex Gaussian vectors, yielding an exact conditional bit error probability (BEP) with no Gaussian approximation. Averaging it over $κ$-$μ$ fading and the reused energy gives the exact BEP for arbitrary weights. Because that energy is shared, its deep fades are common to every branch, and the observation length caps the diversity order at $\min(Mμ,N)$. The deflection-optimal weights follow in closed form and interpolate soft combining and power weighting. Measured 65 GHz indoor non-line-of-sight (NLoS) results quantify the trade-off between spatial resources and observation length.

eess.SP↗

arXiv2026

On-Off Digital Noise Modulation with Fluid Antenna Systems over $κ$-$μ$ Fading Channels

This letter proposes the integration of on-off digital noise (OODN) modulation with fluid antenna systems (FASs). A unified analytical framework is developed to evaluate the performance of FAS- assisted OODN receivers over additive white Gaussian noise and generalized \k{appa}-μ fading channels. The analysis incorporates fluid antenna port selection, the number of available ports, and spatial correlation. Analytical expressions for the average bit error probability are derived and the achievable diversity order is characterized. All expressions are validated through Monte Carlo simulations. Results demonstrate that the spatial diversity provided by the FAS significantly enhances the reliability of OODN transmissions while preserving their inherent low-complexity, non-coherent operation without carrier-phase recovery. The proposed framework establishes a new research direction for energy-efficient Internet of Things (IoT) and machine-type communication systems.

eess.SP↗

arXiv2026

On--Off Digital Noise Modulation under Multi-User Co-Channel Interference

This letter analyzes the performance of on-off digital noise (OODN) modulation under multi-user scenarios. While prior works have addressed single-link operation, the impact of co-channel interference remains unexplored. We consider $K$ synchronous OODN interferers over AWGN and fading channels and derive a unified analytical framework for the bit error probability (BEP). The optimal likelihood-ratio detection threshold is obtained, along with a closed-form expression for the resulting irreducible error floor, which climbs geometrically with the number of co-channel interferers and yields a simple admission-control rule on network density. The analysis is extended to $κ$-$μ$ fading, covering practical millimeter-wave channels with dominant line-of-sight components. Results, corroborated by Monte Carlo simulation, show that the floor is governed by the on-off interference and the non-coherent detector rather than by the noise waveform.

eess.SP↗

arXiv2026

Channel Estimation for Flexible Intelligent Metasurface Aided MIMO Communications

Flexible Intelligent Metasurfaces (FIMs) enable wireless systems to adapt their three-dimensional geometry through morphing, thereby providing new spatial degrees of freedom. However, continuous deformation complicates the accurate acquisition of Channel State Information (CSI). This work proposes a multidimensional framework for MIMO systems with active FIM arrays at both the transmitter and receiver. A split single-time-scale training protocol sequentially introduces spatial variation by morphing the receiver, then the transmitter. The resulting signal model is formulated as a PARAFAC decomposition, and an alternating least squares (ALS) algorithm is employed to estimate steering matrices and path gains. Our numerical results show that the proposed channel estimation method yields accurate CSI recovery for different system setups.

eess.SP↗