A nonuniform DPLL architecture for optimized performance

This paper presents the design, analysis, simulation, and implementation of the architecture of a new nonuniform-type digital phase-locked loop (DPLL). The proposed loop uses a composite phase detector (CPD), which consists of a sample-and-hold unit and an arctan block. The CPD improves the system linearity and results in a wider lock range. In addition, the loop has an adaptive controller block, which can be used to minimize the overall system sensitivity to variations in the power of the input signal. Furthermore, the controller has a tuning mechanism that gives the designer the flexibility to customize the loop parameters to suit a particular application. These performance parameters include lock range, acquisition time, phase noise or jitter, and signal-to-noise ratio enhancement. The simulation results show that the proposed loop provides flexibility to optimize the major conflicting system parameters. A prototype of the proposed system was implemented using a field-programmable gate array (FPGA), and the practical results concur with those obtained by simulation using MATLAB/Simulink. © 2013 Institute of Electrical Engineers of Japan.Published versio

Self-optimization of pilot power in enterprise femtocells using multi objective heuristic

Deployment of a large number of femtocells to jointly provide coverage in an enterprise environment raises critical challenges especially in future self-organizing networks which rely on plug-and-play techniques for configuration. This paper proposes a multi-objective heuristic based on a genetic algorithm for a centralized self-optimizing network containing a group of UMTS femtocells. In order to optimize the network coverage in terms of handled load, coverage gaps, and overlaps, the algorithm provides a dynamic update of the downlink pilot powers of the deployed femtocells. The results demonstrate that the algorithm can effectively optimize the coverage based on the current statistics of the global traffic distribution and the levels of interference between neighboring femtocells. The algorithm was also compared with the fixed pilot power scheme. The results show over fifty percent reduction in pilot power pollution and a significant enhancement in network performance. Finally, for a given traffic distribution, the solution quality and the efficiency of the described algorithm were evaluated by comparing the results generated by an exhaustive search with the same pilot power configuration

BROSMAP: A Novel Broadcast Based Secure Mobile Agent Protocol for Distributed Service Applications

Mobile agents are smart programs that migrate from one platform to another to perform the user task. Mobile agents offer flexibility and performance enhancements to systems and service real-time applications. However, security in mobile agent systems is a great concern. In this paper, we propose a novel Broadcast based Secure Mobile Agent Protocol (BROSMAP) for distributed service applications that provides mutual authentication, authorization, accountability, nonrepudiation, integrity, and confidentiality. The proposed system also provides protection from man in the middle, replay, repudiation, and modification attacks. We proved the efficiency of the proposed protocol through formal verification with Scyther verification tool

Reputation-Aware Relay Selection With Opportunistic Spectrum Access : A Blockchain Approach

The highly dynamic nature of cognitive radio (CR) systems and their stringent latency requirements pose a significant challenge in the realization of efficient intelligent transport systems (ITS). In this paper, we investigate relay selection and opportunistic spectrum access in conjunction with blockchain technology in a secure manner. Specifically, we propose a cross-layer method for secure relay selection, where secondary relays (SRs) are granted access to available spectrum bands based on the balance of their respective virtual wallets. These virtual wallets, which are built based on the SRs' secrecy capacity and their behavior in the network, are the predominant factors that allow SRs to participate in an auction model. To quantify the trustworthiness of the SRs, we formulate a mathematical framework to evaluate the trust value of each SR, which is then leveraged for rewarding or penalizing the SR. Also, we develop an offline blockchain framework to store the information of participating relays and make it available for future operations, to detect reputable and non-reputable relays in the presence of multiple eavesdroppers. The stored reputations of the participating relays are used to develop a self-learning algorithm to exclude the non-reputable relays from the selection group. Finally, we present thorough numerical results to demonstrate the superiority of the proposed system in terms of security, credibility, and integrity.Peer reviewe

Digital phase lock loops: architectures and applications

Digital phase lock loops are critical components of many communication, signal processing and control systems. This exciting new book covers various types of digital phase lock loops. It presents a comprehensive coverage of a new class of digital phase lock loops called the time delay tanlock loop (TDTL). It also details a number of architectures that improve the performance of the TDTL through adaptive techniques that overcome the conflicting requirements of the locking rage and speed of acquisition. These requirements are of paramount importance in many applications including wireless communications, consumer electronics and others. Digital Phase Lock Loops then illustrates the process of converting the TDTL class of digital phase lock loops for implementation on an FPGA-based reconfigurable system. These devices are being utilized in software-defined radio, DSP-based designs and many other communication and electronic systems to implement complex high-speed algorithms. Their flexibility and reconfigurability facilitate rapid prototyping, on-the-fly upgradeability, and code reuse with minimum effort and complexity. The practical real-time results, of the various TDTL architectures, obtained from the reconfigurable implementations are compared with those obtained through simulations with MATLAB/Simulink. The material in this book will be valuable to researchers, graduate students, and practicing engineers

Explicit research skill development within problem/project based learning approach

Problem/Project Based Learning is an innovative teaching model that proved to be effective in a number of disciplines. The common quality that is needed by students taught using this model, whether they are at school, vocational and training (VET) collage, undergraduate programs, and most importantly higher education degrees, is research skill development. However, the concept of skills development and how to do so is not usually clear from students' point of view, while from some educators' point of view such skills are acquired by osmosis through interaction with peers, seniors, or experienced researchers. In this paper, we demonstrate the use of the Research Skill Development (RSD) framework by educators to conceptualize an explicit development of these skills as part of their course delivery. In this paper, we propose to utilize the strengths of RSD framework with problem/project-Based Learning (PBL) to result in explicit research development, which is usually a critical component of PBL model. Pilot studies in two universities were carried out, and improvements in the technical paper quality and research outputs have been observed.Said Al-Sarawi, Mahmoud Al-Qutayri, Brian Ng and Mohammed Ismai