Modern home automation systems include features that enhance security, such as cameras and radars. This paper proposes an innovative home security system that can detect burglars by analyzing acoustic signals and instantly notifying the authorized person(s). The system architecture incorporates the concept of the Internet of Things (IoT), resulting in a network and a user-friendly system. The proposed system uses an adaptive detection algorithm, namely the “short-time-average through long-time-average” algorithm. The proposed algorithm is implemented by an IoT device (Arduino Duo) to detect people’s acoustical activities for the purpose of home/office security. The performance of the proposed system is evaluated using 10 acoustic signals representing actual events and background noise. The acoustic signals were generated by the sounds of keys shaking, the falling of a small object, the shrinking of a plastic bag, speaking, footsteps, etc. The effects of different algorithms’ parameters on the performance of the proposed system have been thoroughly investigated.

This paper proposes an underwater free-space optical code division multiple-access (FSO-CDMA) communication system that integrates differential pulse position modulation (DPPM) with a developed hybrid prime code (HPC) and Manchester encoding, alongside a multiple-access interference cancellation (MAIC) receiver. The system is designed to address the challenges posed by underwater turbulence, absorption, and scattering. A 1-watt laser source operating at a wavelength of 455 nm is utilized to mitigate these effects, thereby reducing link absorption, scattering, and attenuation. The MAIC receiver is employed to minimize noise and interference, significantly enhancing the system’s bit-error rate (BER) performance under turbulent conditions. The paper details the construction and correlation analysis of the HPC, and investigates both instantaneous and average BER performance based on the proposed modulation-coding technique and MAIC receiver. Results demonstrate that the proposed system achieves a 438 m link distance with an 8.33 Gbps data rate and 1.33 Tbps × user network throughput over a 184,900 m² coverage area, maintaining a BER of 10⁻⁹.

Coded caching has been shown to result in significant throughput gains, but its gains were proved only by assuming a placement phase with no transmission cost. A free placement phase is, however, an unrealistic assumption that could stand as an obstacle towards delivering the promise of coded caching. In [1], we relaxed this assumption by introducing a general caching framework that captures transmission costs for both delivery and placement phases under general assumptions on varying network architectures, memory constraints, and traffic patterns. Here, we leverage this general framework and focus on analyzing the effect of the placement communication cost on the overall throughput and the structure of the optimal caching scheme, under the assumptions of the worst case traffic pattern and unlimited memory at the end users. Interestingly, we find relevant network configurations where uncoded caching is the optimal solution.