Topic Review
Blockchain Oracle Problem
The Blockchain Oracle Problem refers to the inability of confirming the veracity of the data collected by oracles. Also, depending on the type, the chances of malfunction, and deliberate tampering. 
  • 5726
  • 11 Nov 2020
Topic Review
TCP-based Congestion Control Algorithms
In today’s data networks, the main protocol used to ensure reliable communications is the transmission control protocol (TCP). The TCP performance is largely determined by the used congestion control (CC) algorithm, which main purpose is to avoid the congestion of the network that can be caused by a large burst of data traffic. TCP CC algorithms have evolved over the past three decades and a large number of CC algorithm variations have been developed to accommodate various communication network environments. Considering the importance of CC in communication networks, the fundamentals of the TCP as the main transport layer protocol and CC process have been explained in detail. Also, an encyclopedic overview of the most popular single-flow and multi-flow TCP CC algorithms with corresponding alternatives has been present. Future directions in the possible improvement of CC algorithms for implementation in complex heterogeneous networks composed of wired and wireless elements are lastly discussed in this encyclopedic work. 
  • 4556
  • 21 Jul 2021
Topic Review
Free-Space Optical Communication
Fast communication is of high importance. Recently, increased data demand and crowded radio frequency spectrum have become crucial issues. Free-Space Optical Communication (FSOC) has diametrically changed the way people exchange information. As an alternative to wire communication systems, it allows efficient voice, video, and data transmission using a medium like air. Due to its large bandwidth, FSOC can be used in various applications and has therefore become an important part of our everyday life. The main advantages of FSOC are a high speed, cost savings, compact structures, low power, energy efficiency, a maximal transfer capacity, and applicability. The rapid development of the high-speed connection technology allows one to reduce the repair downtime and gives the ability to quickly establish a backup network in an emergency. Unfortunately, FSOC is susceptible to disruption due to atmospheric conditions or direct sunlight. Here, we briefly discuss Free-Space Optical Communication from mirrors and optical telegraphs to modern wireless systems and outline the future development directions of optical communication.
  • 2327
  • 11 Nov 2020
Topic Review
Synthetic Aperture Radar
SAR constellations 
  • 1939
  • 24 Aug 2020
Topic Review
Digital Image Watermarking Techniques
Image authentication is an extremely significant concern for the digital revolution, as it is easy to alter any image. In the last few decades, it has been an urgent concern for researchers to ensure the authenticity of digital images. Based on the desired applications, several suitable watermarking techniques have been developed to mitigate this concern. However, it is tough to achieve a watermarking system that is simultaneously robust and secure. This paper gives details of standard watermarking system frameworks and lists some standard requirements that are used in designing watermarking techniques for several distinct applications. The current trends of digital image watermarking techniques are also reviewed to find state-of-the-art methods and their limitations. Some conventional attacks are discussed, and future research directions are given.
  • 1283
  • 29 Oct 2020
Topic Review
HVAC Systems of Smart Building
Early fault detection and diagnosis in heating, ventilation and air conditioning (HVAC) systems may reduce the damage of equipment, improving the reliability and safety of smart buildings, generating social and economic benefits. Data models for fault detection and diagnosis are increasingly used for extracting knowledge in the supervisory tasks. This article proposes an autonomic cycle of data analysis tasks (ACODAT) for the supervision of the building’s HVAC systems. Data analysis tasks incorporate data mining models for extracting knowledge from the system monitoring, analyzing abnormal situations and automatically identifying and taking corrective actions. This article shows a case study of a real building’s HVAC system, for the supervision with our ACODAT, where the HVAC subsystems have been installed over the years, providing a good example of a heterogeneous facility. The proposed supervisory functionality of the HVAC system is capable of detecting deviations, such as faults or gradual increment of energy consumption in similar working conditions. The case study shows this capability of the supervisory autonomic cycle, usually a key objective for smart buildings.
  • 1267
  • 01 Jun 2021
Topic Review
Time Synchronization
Time (or clock) synchronization is a large and vital field of research, as synchronization is a precondition for many applications. A few example applications are distributed data acquisition, distributed databases, and real-time communication.
  • 1105
  • 08 Dec 2020
Topic Review
Connectivity Architecture
Connectivity architecture connects main functional blocks or entities of a system with well-defined interfaces enabling interoperability, fluent data flows and information sharing in timely manner. Local connectivity architecture defines e.g. the architecture inside an autonomous ship. The wider-scale architecture includes geographically distributed entities such as vessels, databases, and remote operations centers.
  • 1039
  • 17 Aug 2020
Topic Review
Internet of Things
The Internet of Things (IoT) refers to a system of interrelated, internet-connected objects that are able to collect and transfer data over a wireless network without human intervention. The term IoT has been considered as an expanding technique applied in various applications and functions, from smart environments and houses to personal healthcare and others [1]. It is described as a smart concept for the internet relating everything to the Internet and data organization and information exchange [2]. The key features required for employing a large-scale IoT are low-cost sensors, highspeed and error-tolerant data communications, smart computations, and numerous applications.
  • 961
  • 26 Oct 2020
Topic Review
Remote Attestation
Remote Attestation (RA) is a security mechanism to remotely detect adversarial presence on untrusted devices in order to guarantee their trustworthiness. RA runs as a two-party security protocol in which a trusted party (i.e., verifier) assures the integrity of the untrusted remote device (i.e., prover). Software-based RA approaches aim at verifying device integrity without relying on specialized hardware components. Despite their limited security guarantees, software-based RA approaches bring opportunities in attesting legacy and resource-constrained Internet of Things (IoT) devices, in which the presence of a hardware root-of-trust is not always a realistic assumption.
  • 910
  • 31 Jan 2022
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