REV Journal on Electronics and Communications
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Proposal of MIMO Ultra-Wide Band Antenna with Low Mutual Coupling
Get PDFIn this paper, a new ultra-wide band (UWB) MIMO antenna is proposed. A MIMO antenna set consists of two single ultra-wide band antennas. This simple and compact MIMO antenna, which is designed to work from 3.1 GHz to 10.6 GHz, has a broad bandwidth with the VSWR ≤ 2. In addition, MIMO antenna characteristics such as radiation pattern, maximal gain are thoroughly investigated
An Adaptive Bandwidth Notch Filter for GNSS Narrowband Interference Mitigation
Get PDFThe low level of received signals power makes Global Navigation Satellite Systems (GNSS) receivers vulnerable to many classes of disturbing signals. Among them, narrow band interference (NBI) might cause serious receiver performance degradation. Cancellation of NBI can be implemented by using notch filters (NF), which are controlled by two parameters: the notch frequency, which specifies the band center, and the notch bandwidth, which defines the spectrum area to be removed. The literature on the topic focuses on adapting the notch frequency, without estimating the filter bandwidth. This paper proposes a method able to determine both the notch parameters, optimizing the interference suppression. The performance analysis shows a good improvement by using the adaptive bandwidth notch filter
A Low Cost and Low Power Consumption Automatic Water Meter Reading System: Hardware Investigation and Network Design
Get PDFThis paper presents a low power consumption and low cost automatic data collection network for water meter application. Based on transmission performance and power consumption, several low cost sub-GHz wireless transceivers are analyzed and compared, and consequently a suitable hardware is chosen. The associated network protocol stack is also examined. To construct the automatic collecting data mechanism, we consider a cluster based wireless sensor network (WSN) where routers and a GPRS gateway are used to link each cluster to a data collection center. Advantages of this proposed configuration are the simple implementation, low cost and low power consumption. By using the Monte Carlo simulation technique, packet delivery ratio and power consumption for different topologies are investigated. Based on obtained results, the optimum network topology for automatic water meter reading in a typical urban environment is finally proposed
High-Level Modeling and Simulation of a Novel Reconfigurable Network-on-Chip Router
Get PDFIn this paper, we present a novel router architecture for implementing a Reconfigurable Network-on-Chip (RNoC) at high-level design using SystemC. The RNoC is an adaptive NoC-based system-on-chip providing a dynamic reconfigurable communication mechanism. By adding a virtual port – named Routing Modification port – into the conventional router architecture, the network router is able to route communication data flexibly whenever the target routing path is blocked, by unwanted defects or intently by a software programme to meet the requirements of applications. The proposed architecture has been modeled in SystemC/C++, simulated and verified within a 2D mesh 5×5 network platform. In normal communication mode, the static XY routing algorithm is used while the West-First algorithm with a proposed prohibited router surrounding technique is applied in reconfiguration mode. Experimental results are also reported to compare the performance of the network architecture in different operation modes as well as with other works
A Complete Method for Reconstructing an Elevation Surface of 3D Point Clouds
Get PDFReconstructing the surface of 3D point clouds is a reconstruction from a cloud of 3D points to a triangular mesh. This process approximates a discrete point cloud by a continuous/smooth surface depending on the input data and the applications of users. In this paper, we propose a complete method to reconstruct an elevation surface from 3D point clouds. The method consists of three steps. In the first step, we triangulate an elevation surface of 3D point cloud structured in a 3D grid. In the second step, we remove the outward triangles to deal with concave regions on the boundary of the triangular mesh. In the third step, we reconstruct this surface by filling the hole of triangular mesh. Our method could process very fast for triangulating the surface, preserve the topology and characteristic of the input surface after reconstruction
Multi-level Scalable Textual-Graphical Password Authentication Scheme for Web based Applications
Get PDFNowadays, user authentication is one of the important topics in information security. Authentication is necessary in multi-user systems. User name and password are used to authenticate a user. Text-based strong password scheme can provide security to a certain degree. Users tend to pick short passwords or passwords that are easy to remember, which makes the passwords vulnerable for attackers to break. Furthermore, textual password is vulnerable to shoulder-surfing, hidden camera and spy-ware attacks. Graphical authentication has been proposed as a possible alternative solution to text-based authentication, motivated particularly by the fact that humans can remember images better than text. However, they are mostly vulnerable to shoulder surfing. In this paper, we propose a Multi-level Scalable Textual-Graphical Password Authentication Scheme for web based applications. This scheme integrates both graphical and textual password schemes, and provides multi-level authentication scheme as compared to previously proposed single level scheme. In this scheme multi-level authentication is obtained by making use of SMS service, hence provides more secure service. This scheme shows significant potential bridging the gap between conventional textual password and graphical password. Further enhancements of this scheme are proposed and briefly discussed
Toward A Full Implementation of the Operation and Support Subsystem (OSS) in IMS Networks
Get PDFRecently, mobile operators all over the world are facing big challenges on the decreasing of the revenues from its traditional killer-applications like SMS/MMS and even voice services. The challenges come from a new trend of services called OTT (Over The Top). These OTT services provide the mobile users with flexible, convenient and more importantly free means to do their daily multimedia communication needs and seamlessly without any border so that operators couldn’t be just simply block it, but in opposite, need to find solutions to compete against it. Because of that, nowadays, more and more operators choose to deploy the standard RCS (Rich Communication Suite). RCS is a set of rich features communication services developed on top of IMS framework. Although there have been tremendous efforts to develop the architecture and protocols for IMS, which is a key technology of the NGN, it is far from being widely deployed. There are many reasons for that unpopularity (of IMS commercial deployment), namely, the lacking of clear business model for IMS-based services, no big difference between IMS-based services and SOA (Service Oriented Architecture) services, lack of the true demands for features that IMS based services have, etc... However, one of the most important reason that till now not many researchers have pointed out and addressed it, is about the OSS (Operation and Support Subsystem) functions. The lacking of OSS clearly defined functions and interfaces make the difficulties for operators and even equipment manufacturers to collect the pay back for any big scale IMS deployment for their networks. This paper presents our proven that IMS can provide the killer applications with blending features like mash-up and readily equipped with the intelligent charging and policy control functions. That may partly help to speed up the deployment process of IMS in real networking environment
Chaotic Compressed Sensing and Its Application to Magnetic Resonance Imaging
Get PDFFast image acquisition in magnetic resonance imaging (MRI) is important, due to the need to find ways that help relieve patient’s stress during MRI scans. Methods for fast MRI have been proposed, most notably among them are pMRI (parallel MRI), SWIFT (SWeep Imaging with Fourier Transformation), and compressed sensing (CS) based MRI. Although it promises to significantly reduce acquisition time, applying CS to MRI leads to difficulties with hardware design because of the randomness nature of the measurement matrix used by the conventional CS methods. In this paper, we propose a novel method that combines the above-mentioned three approaches for fast MRI by designing a compound measurement matrix from a series of single measurement matrices corresponding to pMRI, SWIFT, and CS. In our method, the CS measurement matrix is designed to be deterministic via chaotic systems. This chaotic compressed sensing (CCS) measurement matrix, while retaining most features of the random CS matrix, is simpler to realize in hardware. Several compound measurement matrices have been constructed and examined in this work, including CCS-MRI, CCS-pMRI, CCS-SWIFT, and CCS-pSWIFT. Simulation results showed that the proposed method allows an increase in the speed of the MRI acquisition process while not compromising the quality of the acquired MR images
An Overview of H.264 Hardware Encoder Architectures Including Low-Power Features
Get PDFH.264 is the most popular video coding standard with high potent coding performance. For its efficiency, the H.264 is expected to encode real-time and/or high-definition video. However, the H.264 standard also requires highly complex and long lasting computation. To overcome these difficulties, many efforts have been deployed to increase encoding speed. Besides, with the revolution of portable devices, multimedia chips for mobile environments are more and more developed. Thus, power-oriented design for H.264 video encoders is currently a tremendous challenge. This paper discusses these trends and presents an overview of the state of the art on power features for different H.264 hardware encoding architectures. We also propose the VENGME’s design, a particular hardware architecture of H.264 encoder that enables applying low-power techniques and developing power-aware ability. This low power encoder is a four-stage architecture with memory access reduction, in which, each module has been optimized. The actual total power consumption, estimated at Register-Transfer-Level (RTL), is only 19.1 mW