Enhanced Filterless Multi-Color VLC via QCT

Color shift keying (CSK) in visible light communication (VLC) often suffers from filter-induced crosstalk and reduced brightness. This paper proposes using quartered composite transform (QCT) with multi-color light-emitting diodes (LEDs) to improve both illumination and communication. The proposd DC-biased QCT scheme eliminates receiver optical filters, thereby removing crosstalk and significantly increasing signal-to-noise ratio (SNR). Simulations demonstrate QCT maintains high illumination quality (CRI 79.72, CCT 3462 K) while achieving over double the average illuminance compared to CSK under the same power budget. QCT also shows better bit error rate (BER) performance in low-to-moderate SNR regimes and has ability to convert multi-tap frequency-selective channel into an equivalent single-tap flat-fading channel to mitigate inter-symbol interference (ISI), proving a promising technique for brighter, high-performance, filter-less VLC.

xApp Conflict Mitigation with Scheduler

Open RAN (O-RAN) fosters multi-vendor interoperability and data-driven control but simultaneously introduces the challenge of managing pre-trained xApps that can produce conflicting actions. Although O-RAN specifications mandate offline training and validation to prevent untrained models, operational conflicts remain likely under dynamic, context-dependent conditions. This work proposes a scheduler-based conflict mitigation framework to address these challenges without requiring training xApps together or further xApp re-training. By examining an indirect conflict involving power and resource block allocation xApps and employing an Advantage Actor-Critic (A2C) approach to train both xApps and the scheduler, we illustrate that a straightforward A2C-based scheduler improves performance relative to independently deployed xApps and conflicting cases. Notably, augmenting the system with baseline xApps and allowing the scheduler to select from a broader pool yields the best results, underscoring the importance of adaptive scheduling mechanisms. These findings highlight the context-dependent nature of conflicts in automated network management, as two xApps may conflict under certain conditions but coexist under others. Consequently, the ability to dynamically update and adapt the scheduler to accommodate diverse operational intents is vital for future network deployments. By offering dynamic scheduling without re-training xApps, this framework advances practical conflict resolution solutions while supporting real-world scalability.

A Novel Pre-Coding Based PAPR Reduction Scheme for IM/DD Systems

Orthogonal frequency division multiplexing (OFDM) is critical for high-speed visible light communication (VLC) transmission; however, it suffers from a high peak-to-average power ratio (PAPR) problem. Among PAPR reduction techniques, pre-coding methods have shown promising advantages such as signal independence and no requirement for signaling overhead. In this paper, we present a novel pre-coding method that combines discrete cosine transform (DCT) and discrete sine transform (DST) for VLC systems using OFDM. Our proposed approach, tailored specifically for intensity modulation and direct detection (IM/DD) systems, aims to further improve the PAPR reduction while preserving bit error rate (BER) performance. Simulation results demonstrate that the proposed method achieves more than a 6 dB reduction in PAPR compared to the DCT pre-coded method without significant degradation in BER performance.