An overview of spectrum sensing techniques for cognitive LTE and LTE-A radio systems

Advanced communication systems, such as long term evolution (LTE) and LTE-advanced (LTE-A) systems, promise to increase the number of users with high-speed data exchange. However, it leads to spectrum scarcity because of the huge size of data exchange with limited spectrum resources. Cognitive radio (CR) technique is considered the best solution for this spectrum scarcity problem. Spectrum sensing (SS), one of the CR techniques is used to detect the spectrum hole of primary user (PU) without interference with PU. In this paper, several SS approaches for LTE and LTE-A systems are investigated in the CR system. These SS approaches are based on two techniques, namely energy detection and cyclostationary feature detection techniques. The first technique includes four approaches of auto-correlation based advanced energy, time domain detection, Welch periodogram and two-stage model algorithms, while the second technique contains two approaches, namely pilot induced cyclostationary and second order cyclostationary algorithms. According to the analysis, the two-stage model and the second order cyclostationary algorithms are better than the other algorithms because they produce accurate results at the expense of system complexity. Hence, in general a good SS algorithms would require some trade-off between complexity and accuracy.     

A Framework for Evaluating the System Penalty From Polarization-Mode Dispersion Using Different Performance Monitoring Techniques

We present a theoretical framework relating system penalties from polarization-mode dispersion (PMD) to various monitoring techniques for non-return-to-zero systems. The framework includes models for string length, radio-frequency spectral power, eye opening, and degree of polarization. We validate the models experimentally and show that they are interrelated by common constants specific to the system under investigation.      

Three-dimensional multi-beam adaptive arrays

The multi-beam antenna systems have become increasingly important in modern communications. In this paper, the author proposes according to the properties of array radiation space the use of the LMS’ adaptive techniques in multi-beam antenna systems. This proposal includes the radiation pattern of three-dimensional adaptive arrays, the evolution of the radiation pattern of adaptive arrays, the signal-to-interference plus noise ratio of the array system output, and the structure of the adaptive multi-beam networks. These will be discussed in the order mentioned.     

微波光子技术的研究进展

微波光子技术是融合微波技术和光子技术的一门新兴前沿技术,它集成了无线通信的灵活性和光通信的大容量特性、低损耗和抗电磁干扰等特性而迅速成为研究热点.介绍了微波光子系统的基本构想和几种关键技术,回顾和展望微波光子技术的应用以及未来的研究动向.     

Multiple-access techniques for commercial satellites

The unique multipoint interconnection capabilities of satellite communication networks place a burden on the communications system designer to achieve highly efficient transmission capacity in the face of a very wide range of network requirements. The ability of various types of multiple-access systems to meet these requirements is the subject of this paper. INTELSAT, recognizing that the frequency division multiplex-frequency modulation, frequencY division multiple access (FDM-FM-FDMA) method it currently uses has advantages in some applications but is not optimum for the multiple-access environment, has supported the development of two-digital multiple-access communications techniques: single channel per carrier frequency division multiple access (SPADE) and time division multiple access (TDMA). These two techniques are discussed in detail and the paper concludes with a presentation of a promising multiple-access technique of the future which includes time division switching on board the satellite.     

Economic aspects of advanced energy technologies

Advanced energy technologies span a wide variety of resources, techniques, and end-user requirements. Economic considerations are major factors that shape their harnessing and utilization. A discussion of the basic factors in the economic arena is presented, with particular emphasis on renewable energy technologies-photovoltaics, solar-thermal, wind-electric conversion, biomass utilization, hydro, and tidal and wave energy systems. The following are viewed as essential to determine appropriate energy system topologies: proper resource-need matching with an eye on the quality of energy requirements, integrated use of several resources and technologies, and a comprehensive consideration which includes prospecting, collection, conversion, transportation, distribution, storage and reconversion, end use, and subsequent waste management aspects. A few case studies are included to show the status of some of the key technologies and systems     

Beam Forming in Smart Antenna with Precise Direction of Arrival Estimation Using Improved MUSIC

Smart antenna is now commonly used in communication systems due to its high advantages. In order to improve the performance of smart antenna operation, efficient design of beam forming pattern is required based on the subjected antenna parameters. In the previous works, beam forming techniques were proposed using hybridization of soft computing techniques, however the precision has not been considered in terms of direction of arrival (DOA). This paper includes DOA while deriving the beam forming pattern of smart antenna. To estimate precise DOA, the MUSIC algorithm is improved by introducing a tuned correlation matrix after solving the objective model for the matrix. Thus estimated DOA pattern is more precise as the unwanted side lobes are suppressed when compared to the conventional DOA pattern. Based on the estimated DOA pattern, the antenna beam forming pattern is derived as per the required direction of angles. The experimental results show the performance of the proposed beam forming technique over the previous techniques.     

Simulation System for Analog and Digital Transmissions

In this paper a complete communication system simulation package is described, which includes digital as well as analog operations to be performed on the signal to be transmitted. The package simulates the transmitter, the communication channel, and the receiver. The digital transmission simulation considers data communication systems with digital filtering, source and channel coding performing the operations of transmitter coding and receiver decoding. The two coding operations can be realized both separately and independently and in a strictly connected or "integrated" form. The analog transmission simulation includes the modulator, the transmitter pulse shaping filter, the communication channel, the receiving filter, and the demodulator. This section is very general, so that it allows the simulation of both analog and digital transmissions. Simulation results are presented regarding some combinations of the following techniques: predictive source coding, block codes able to correct random and burst errors, and modulation techniques such as AM,M-level PSK, FSK, and MSK. In particular, the paper presents the results of the analyses of an integrated source-channel coding applied to digital transmissions and of a system transmitting both voice and data for a VHF communication link between ground and aircraft for air traffic control applications.     

Normalization and dropout for stochastic computing-based deep convolutional neural networks

Recently, Deep Convolutional Neural Network (DCNN) has been recognized as the most effective model for pattern recognition and classification tasks. With the fast growing Internet of Things (IoTs) and wearable devices, it becomes attractive to implement DCNNs in embedded and portable systems. However, novel computing paradigms are urgently required to deploy DCNNs that have huge power consumptions and complex topologies in systems with limited area and power supply. Recent works have demonstrated that Stochastic Computing (SC) can radically simplify the hardware implementation of arithmetic units and has the potential to bring the success of DCNNs to embedded systems. This paper introduces normalization and dropout, which are essential techniques for the state-of-the-art DCNNs, to the existing SC-based DCNN frameworks. In this work, the feature extraction block of DCNNs is implemented using an approximate parallel counter, a near-max pooling block and an SC-based rectified linear activation unit. A novel SC-based normalization design is proposed, which includes a square and summation unit, an activation unit and a division unit. The dropout technique is integrated into the training phase and the learned weights are adjusted during the hardware implementation. Experimental results on AlexNet with the ImageNet dataset show that the SC-based DCNN with the proposed normalization and dropout techniques achieves 3.26% top-1 accuracy improvement and 3.05% top-5 accuracy improvement compared with the SC-based DCNN without these two essential techniques, confirming the effectiveness of our normalization and dropout designs.     

Evaluating sustainable energy harvesting systems for human implantable sensors

Achieving most appropriate energy-harvesting technique for human implantable sensors is still challenging for the industry where keen decisions have to be performed. Moreover, the available polymeric-based composite materials are offering plentiful renewable applications that can help sustainable development as being useful for the energy-harvesting systems such as photovoltaic, piezoelectric, thermoelectric devices as well as other energy storage systems. This work presents an expert-based model capable of better evaluating and examining various available renewable energy-harvesting techniques in urban surroundings subject to various technical and economic, often conflicting, criteria. Wide evaluation criteria have been adopted in the proposed model after examining their suitability as well as ensuring the expediency and reliability of the model by worldwide experts’ feedback. The model includes establishing an analytic hierarchy structure with simultaneous 12 conflicting factors to establish a systematic road map for designers to better assess such techniques for human implantable medical sensors. The energy-harvesting techniques considered were limited to Wireless, Thermoelectric, Infrared Radiator, Piezoelectric, Magnetic Induction and Electrostatic Energy Harvesters. Results have demonstrated that the best decision was in favour of wireless-harvesting technology for the medical sensors as it is preferable by most of the considered evaluation criteria in the model.     

Display-device research and development in Japan

Current work on display devices in Japan is surveyed. Work on plasma display panels includes several methods for producing gray scale on ac-driven bistable panels, a technique for moving the display on an ac-driven panel, and new types of plasma display panels. Development on several types of alphanumeric displays, including both new and older types, is summarized. Work on light-emitting diodes includes new fabrication techniques and new types of devices. The liquid-crystal work described includes addressing techniques, color modulators, and light-addressed light valves. A new cathodochromic display tube, a high-frequency oscilloscope tube, and an electroluminescent display panel are mentioned.     

Adaptive feedback control

Adaptive control is now finding its way into the marketplace after many years of effort. This paper reviews some ideas used to design adaptive control systems. It covers early ideas which primarily attempt to compensate for gain variations and more general methods like gain scheduling, model reference adaptive control, and self-tuning regulators. It is shown that adaptive control laws can be obtained using stochastic control theory. Techniques for analyzing adaptive systems are discussed. This covers stability and convergence analysis. Issues of importance for applications like parameterization, tuning, and tracking, as well as different ways of using adaptive control are also discussed. An overview of applications which includes feasibility studies as well as products based on adaptive techniques concludes the paper.     

End-to-end WAN service availability

This paper seeks to understand how network failures affect the availability of service delivery across wide-area networks (WANs) and to evaluate classes of techniques for improving end-to-end service availability. Using several large-scale connectivity traces, we develop a model of network unavailability that includes key parameters such as failure location and failure duration. We then use trace-based simulation to evaluate several classes of techniques for coping with network unavailability. We find that caching alone is seldom effective at insulating services from failures but that the combination of mobile extension code and prefetching can improve average unavailability by as much as an order of magnitude for classes of service whose semantics support disconnected operation. We find that routing-based techniques may provide significant improvements but that the improvements of many individual techniques are limited because they do not address all significant categories of network failures. By combining the techniques we examine, some systems may be able to reduce average unavailability by as much as one or two orders of magnitude.     

IMPACCT: Methodology and Tools for Power-Aware Embedded Systems

Power-aware systems are those that must exploit a widerange of power/performance trade-offs in order to adapt to the power availabilityand application requirements. They require the integration of many novel powermanagement techniques, ranging from voltage scaling to subsystem shutdown.However, those techniques do not always compose synergistically with eachother; in fact, they can combine subtractively and often yield counterintuitive,and sometimes incorrect, results in the context of a complete system. Thiscan become a serious problem as more of these power aware systems are beingdeployed in mission critical applications.To address the problem of technique integration for power-aware embedded systems, we propose a new design tool framework called IMPACCT and the associated design methodology. The system modeling methodology includes application model for capturing timing/powerconstraints and mode dependencies at the system level. The tool performs power-awarescheduling and mode selection to ensure that all timing/power constraintsare satisfied and that all overhead is taken into account. IMPACCT then synthesizesthe implementation targeting a symmetric multiprocessor platform. Experimentalresults show that the increased dynamic range of power/performance settingsenabled a Mars rover to achieve significant acceleration while using lessenergy. More importantly, our tool correctly combines the state-of-the-arttechniques at the system level, thereby saving even experienced designersfrom many pitfalls of system-level power management.     

Patent Abstracts

Presents a summary of over 25 patents and includes abstracts as well as diagrams, where applicable. Covers such technologies, techniques, and/or methodologies as: area-efficient, digital variable resistor with high resolution; accurate cascode bias networks; amplifier systems with low-noise, constant-transconductance bias generators; programmable boosting and charge neutralization; step-up/step-down (buck/boost) switching regulator control methods; and a voltage-controlled oscillator circuit with analogue and digital actuation.     

Investigations into advanced concepts of terminal and base-stationantennas

The development of essentially new terminal and base-station antennas has become one of the most important tasks in contemporary antenna engineering. Improvements in antenna technology must be accomplished regardless of progress in signal processing. Comprehensive research on such antennas has been carried on at the Wroclaw University of Technology, Poland, for several years now. There are three major fields of interest: small antennas, base-station antennas, and smart-antenna technology. The small antennas investigated-either planar or conformal-approach the physical limits of allowable dimensions. They operate with a number of systems that might involve advanced signal-processing techniques. The scope of the research also includes studies on the interactions between terminal antennas and humans     

Method of reliability analysis of control systems for nuclear power plants

High reliability is one of the main objectives of the design and operation of Control Systems in Nuclear Power Plants. This paper presents a method of reliability analysis for these systems using various reliability techniques and engineering judgement. The step-by-step analysis includes system study, field data, failure mode and effect analysis, common mode failures, fault trees, human factors, reliability targets, and design reviews. To illustrate this method, the Liquid Zone Control System for CANDU nuclear reactor control is used.     

Creating compact models of complex electronic systems: an overview and suggested use of existing model reduction and experimental system identification tools

The electronic system packaging community has a great need to reduce the size of its heat transfer simulations so that it can: simulate and analyze more complex systems, include additional physical phenomena, and improve its ability to search the electronic systems packaging design space. Aside from further improvements in machine speed and numerical algorithm efficiency, this is basically a question of model reduction and experimental identification: one would like to know how to dramatically reduce the size of heat transfer simulations when they are available, and one would further like to identify models directly from experiment when accurate, computationally feasible, numerical simulations are not available (as in the case of turbulent flows through complex geometries). Fortunately, the topic of low-order modeling for design has been widely studied and successfully applied in other fields. This paper gives a brief overview of these techniques, it suggests how these tools might be effectively used for electronic systems including cases that involve unsteady fluid dynamics, and it summarizes some of the reduced-order modeling lessons learned in other fields. The paper includes some initial work in model reducing the unsteady heat conduction equation, a result on component model inter-connections, and an outline of a systems level model for an air cooled personal computer.     

2017年欧洲光通信会议述评

介绍了第43届欧洲光通信会议的概况,评述了主题报告、专题研讨、综述指导报告和特邀报告、截后论文和展览会等内容。按照光纤、光纤器件和光纤放大器,集成光电器件和光处理器,光通信系统数字技术,传输子系统和光网络单元,数据通信和计算机硬件,点到点传输链路,核心、城域和数据中心网络,接入、本地和家庭网络8个方向进行探讨。