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High-speed, reliable, flexible, and cost-effective underwater wireless communication systems have a wide variety of use in scientific, civilian, and commercial domains. Visible light communication (VLC) seems to be a promising candidate in satisfying majority of the requirements listed above. From this perspective, VLC could easily be deployed in heterogeneous wireless networking scenarios with high quality of service. Therefore, in this paper, an adapted LTE frame structure is implemented for underwater VLC (UVLC) system. The performance of UVLC system employing asymmetrically clipped optical orthogonal frequency division multiplexing modulation technique is practically tested by taking channel estimation and synchronization into account. Also, the effects of varying orthogonal frequency division multiplexing parameters on the system's signal-to-noise ratio and the bit-error-rate (BER) performances are studied. The implementation is tested for quadrature phase shift keying and 16-quadrature amplitude modulation techniques supporting both 128-and 1024-points fast Fourier transform configurations, which correspond to data rates of 1.92 and 15.36 Mbps, respectively. Experimental results show that BER could be reduced down to a level on the order of 10 −6 .

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Tasks in modern embedded systems such as automotive and avionics communicate among each other using shared data towards achieving the desired functionality of the whole system. In commodity platforms, cores communicate data through the shared memory hierarchy and correctness is maintained by a cache coherence protocol. Recent works investigated the deployment of coherence protocols in real-time systems and showed significant performance improvements. Nonetheless, we find these works to require modifications to commodity coherence protocols, assume simple in-order pipelines, and most importantly suffer from significant latency delays due to coherence interference along with average performance degradation. In this work, we propose PISCOT : a predictable and coherent bus architecture that (i) provides a considerably tighter bound compared to the state-of-the-art predictable coherent solutions (4 × tighter bounds in a quad-core system). (ii) It does so with a negligible performance loss compared to conventional high-performance architecture coherence delays (less than \(4\% \) for SPLASH-3 benchmarks). This improves average performance by up to 5 × (2.8 × on average) compared to its predictable coherence counterpart. Finally, (iii) it achieves that without requiring any modifications to conventional coherence protocols. We show this by integrating PISCOT on top of two protocols with a detailed implementation with complete transient states: MSI and MESI.

Real-time traffic information can be utilized to enhance the efficiency of transportation networks by dynamically updating routing plans to mitigate traffic jams. However, an interesting question is whether the network coordinator should broadcast real-time traffic information to all network users or communicate it selectively to some of them. Which option enhances the network efficiency more?In this work, we demonstrate using simulation experiments that sharing real-time traffic information with all network users is sub-optimal, and it is actually better to share the information with a majority subset of the total population in order to improve the overall network performance. This result is valid under the assumption that each network user decides it's route to destination locally.

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This paper proposes a low-complexity antenna selection scheme based on large-scale fading to enhance the secrecy performance in independent and non-identical generalized-K fading channels. New analytical results for the secrecy outage probability and the probability of non-zero secrecy capacity are derived when the receiving terminals employ the maximum ratio combining scheme. In addition, simple and insightful approximations are obtained for the secrecy outage probability in the high signal to noise ratio regime, which shed light on the impact of key system parameters on the secrecy performance. Simulation results are provided to validate the analytical expressions.Index Terms-Physical layer security, MIMO channels, largescale TAS, small-scale receive MRC, composite fading.