Before delving into the details of orthogonal frequency division multiplexing (OFDM), relevant background material must be presented first. The purpose of this chapter is to provide the necessary building blocks for the development of OFDM principles. Included in this chapter are reviews of stochastic and random process, discrete-time signals and systems, and the Discrete Fourier Transform (DFT). Tooled with the necessary mathematical foundation, we proceed with an overview of digital communication systems and OFDM communication systems. We conclude the chapter with summaries of the OFDM wireless LAN standards currently in existence and a high-level comparison of single carrier systems versus OFDM.
上傳時間： 2020-05-31
上傳用戶：shancjb
With the advent of IMT-2000, CDMA has emerged at the focal point of interest in wireless communications. Now it has become impossible to discuss wireless communications without knowing the CDMA technologies. There are a number of books readily published on the CDMA technologies, but they are mostly dealing with the traditional spread-spectrum technologies and the IS-95 based CDMA systems. As a large number of novel and interesting technologies have been newly developed throughout the IMT-2000 standardization process in very recent years, new reference books are now demanding that address the diverse spectrum of the new CDMA technologies.
標簽： Communications Scrambling Techniques CDMA for
上傳時間： 2020-06-01
上傳用戶：shancjb
This paper presents a Hidden Markov Model (HMM)-based speech enhancement method, aiming at reducing non-stationary noise from speech signals. The system is based on the assumption that the speech and the noise are additive and uncorrelated. Cepstral features are used to extract statistical information from both the speech and the noise. A-priori statistical information is collected from long training sequences into ergodic hidden Markov models. Given the ergodic models for the speech and the noise, a compensated speech-noise model is created by means of parallel model combination, using a log-normal approximation. During the compensation, the mean of every mixture in the speech and noise model is stored. The stored means are then used in the enhancement process to create the most likely speech and noise power spectral distributions using the forward algorithm combined with mixture probability. The distributions are used to generate a Wiener filter for every observation. The paper includes a performance evaluation of the speech enhancer for stationary as well as non-stationary noise environment.
標簽： Telecommunications Processing Signal for
上傳時間： 2020-06-01
上傳用戶：shancjb
Part I provides a compact survey on classical stochastic geometry models. The basic models defined in this part will be used and extended throughout the whole monograph, and in particular to SINR based models. Note however that these classical stochastic models can be used in a variety of contexts which go far beyond the modeling of wireless networks. Chapter 1 reviews the definition and basic properties of Poisson point processes in Euclidean space. We review key operations on Poisson point processes (thinning, superposition, displacement) as well as key formulas like Campbell’s formula. Chapter 2 is focused on properties of the spatial shot-noise process: its continuity properties, its Laplace transform, its moments etc. Both additive and max shot-noise processes are studied. Chapter 3 bears on coverage processes, and in particular on the Boolean model. Its basic coverage characteristics are reviewed. We also give a brief account of its percolation properties. Chapter 4 studies random tessellations; the main focus is on Poisson–Voronoi tessellations and cells. We also discuss various random objects associated with bivariate point processes such as the set of points of the first point process that fall in a Voronoi cell w.r.t. the second point process.
標簽： Stochastic Geometry Networks Wireless Volume and
上傳時間： 2020-06-01
上傳用戶：shancjb
I love telecommunications. It is powerful and it empowers, with far-reaching consequences. It has demonstrated the potential to transform society and business, and the revolution has only just begun. With the invention of the telephone, human communications and commerce were forever changed: Time and distance began to melt away as a barrier to doing business, keeping in touch with loved ones, and being able to immediately respond to major world events. Through the use of computers and telecommunications networks, humans have been able to extend their powers of thinking, influence, and productivity, just as those in the Industrial Age were able to extend the power of their muscles, or physical self, through use of heavy machinery.
標簽： Telecommunications Essentials
上傳時間： 2020-06-01
上傳用戶：shancjb
In a world where consumers,businesses and organizations are demanding faster,amerter and more seamlessly converged information technology and communization services,concepts such as Driverless Cars,combining advanced automatic controls,artficial intelligences and automotive transport technologies are soon expected to become a commercial realty.At the same time,new blueprints such as industrial internet and industry 4.0 are driving the increased digitization of entire industries and economic sectors,boosting efficiencies and productivity.
標簽： ZTE-M-ICT
上傳時間： 2020-06-01
上傳用戶：shancjb
Static electricity is the most ancient form of electricity known to humans. More than 2000 years ago, the Greeks recognized the attraction between certain mate- rials when they were rubbed together; indeed, the word electricity comes from the Greek elektron, which means amber. During the seventeenth and eighteenth centuries, several key experiments were conducted to understand and measure static electricity. But the discovery of electromagnetism and its formidable break- through has rapidly outgrown interest in static electricity. Even today, where the industrial applications of static electricity are not insignificant, they cannot compare with those of electromagnetism and electrodynamics.
標簽： Understand Discharge Electro Static
上傳時間： 2020-06-05
上傳用戶：shancjb
Electrostatic discharge (ESD) is one of the most prevalent threats to the reliability of electronic components. It is an event in which a finite amount of charge is trans- ferred from one object (i.e., human body) to another (i.e., microchip). This process can result in a very high current passing through the microchip within a very short period of time, and, hence, more than 35% of chip damages can be attributed to an ESD-related event. As such, designing on-chip ESD structures to protect integrated circuits against the ESD stresses is a high priority in the semiconductor industry.
標簽： Electrostatic Protection Discharge
上傳時間： 2020-06-05
上傳用戶：shancjb
Failure analysis is invaluable in the learning process of electrostatic discharge (ESD) and electrical overstress (EOS) protection design and development [1–8]. In the failure analysis of EOS, ESD, and latchup events, there are a number of unique failure analysis processes andinformationthatcanprovidesignificantunderstandingandillumination[4].Today,thereis still no design methodology or computer-aided design (CAD) tool which will predict EOS, ESDprotectionlevels,andlatchupinasemiconductorchip;thisisoneofthesignificantreasons why failure analysis is critical to the ESD design discipline.
標簽： Mechanisms Failure Models ESD and
上傳時間： 2020-06-05
上傳用戶：shancjb
The planarization technology of Chemical-Mechanical-Polishing (CMP), used for the manufacturing of multi- level metal interconnects for high-density Integrated Circuits (IC), is also readily adaptable as an enabling technology in MicroElectroMechanical Systems (MEMS) fabrication, particularly polysilicon surface micromachining. CMP not only eases the design and manufacturability of MEMS devices by eliminating several photolithographic and film issues generated by severe topography, but also enables far greater flexibility with process complexity and associated designs. T
標簽： mechanical polishing Chemical
上傳時間： 2020-06-06
上傳用戶：shancjb
