In this paper we revisit hybrid analog-digital precoding systems with emphasis on their modelling and radio-frequency (RF) losses, to realistically evaluate their benefits in 5G system implementations. For this, we decompose the analog beamforming networks (ABFN) as a bank of commonly used RF components and formulate realistic model constraints based on their S-parameters. Specifically, we concentrate on fully-connected ABFN (FC-ABFN) and Butler networks for implementing the discrete Fourier Transform (DFT) in the RF domain. The results presented in this paper reveal that the performance and energy efficiency of hybrid precoding systems are severely affected, once practical factors are considered in the overall design. In this context, we also show that Butler RF networks are capable of providing better performances than FC-ABFN for systems with a large number of RF chains.
标签： Analog-Digital Precoding Hybrid
上传时间： 2020-05-27
上传用户：shancjb
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.
上传时间： 2020-05-31
上传用户：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.
标签： Stochastic Geometry Networks Wireless Volume and
上传时间： 2020-06-01
上传用户：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.
标签： Telecommunications Essentials
上传时间： 2020-06-01
上传用户：shancjb
With all the recent hype over radio frequency identification (RFID) and the requirements to implement it, you might think that RFID can turn water into wine, Transform lead into gold, and cure the world’s diseases. You might also be worried that RFID will enable Big Brother to track your move- ments to within a foot of your location from a satellite five hundred miles up in space. The truth is, RFID can do none of these things. In this chapter, you find out the basics of what RFID is, what forces are dri- ving RFID as a replacement for the bar code in the marketplace, and what benefits RFID can offer
标签： ForDummies_RFID_For_Dummies
上传时间： 2020-06-08
上传用户：shancjb
Signals convey information. Systems Transform signals. This book introduces the mathe- matical models used to design and understand both. It is intended for students interested in developing a deep understanding of how to digitally create and manipulate signals to measure and control the physical world and to enhance human experience and communi- cation.
标签： Interpretation Structure and Signals Systems of
上传时间： 2020-06-10
上传用户：shancjb
Artificial Intelligence (AI) has undoubtedly been one of the most important buz- zwords over the past years. The goal in AI is to design algorithms that Transform com- puters into “intelligent” agents. By intelligence here we do not necessarily mean an extraordinary level of smartness shown by superhuman; it rather often involves very basic problems that humans solve very frequently in their day-to-day life. This can be as simple as recognizing faces in an image, driving a car, playing a board game, or reading (and understanding) an article in a newspaper. The intelligent behaviour ex- hibited by humans when “reading” is one of the main goals for a subfield of AI called Natural Language Processing (NLP). Natural language 1 is one of the most complex tools used by humans for a wide range of reasons, for instance to communicate with others, to express thoughts, feelings and ideas, to ask questions, or to give instruc- tions. Therefore, it is crucial for computers to possess the ability to use the same tool in order to effectively interact with humans.
标签： Embeddings Processing Language Natural in
上传时间： 2020-06-10
上传用户：shancjb
快速傅里叶变换，fft应用实例。供学习，供参考。 原理：快速傅里叶变换 (fast Fourier Transform), 即利用计算机计算离散傅里叶变换（DFT)的高效、快速计算方法的统称，简称FFT。快速傅里叶变换是1965年由J.W.库利和T.W.图基提出的。采用这种算法能使计算机计算离散傅里叶变换所需要的乘法次数大为减少，特别是被变换的抽样点数N越多，FFT算法计算量的节省就越显著。
上传时间： 2021-07-14
上传用户：hhh4321
无线传感网有TDMA和CSMA两种基本的MAC协议方案。欣仰邦LoRa技术实现TDMA算法组网系统，LoRa-TDMA的优点是：低成本实现小规模组网。基于TDMA的MAC协议实现信道分配的机制简单成熟，它没有CSMA竞争机制的碰撞和重传问题，而是为无线传感器网络中每个节点分配独立的时隙用于数据发送或接收TDMA信号的前导字和CZT（chirp z-Transform）算法的高频率分辨率特性，设计了适于低信噪比信号的宽范围载波同步改进算法。数据传输时不需要过多的控制信息，且节点在空闲时能够及时进入睡眠状态.因而在节点无移动且网络部署情况已知的场景，采用TDMWA方式进行通信，可避免信道冲突以及冲突引起的丢包和能量损耗；TDMA信号的前导字进行数据辅助（DA）型载波同步，有效地缩小了低信噪比信号的频偏范围；再利用CZT算法进一步缩小频偏范围，最后利用非数据辅助型（NDA）自相关函数法得到精确的载波频偏。改进算法的计算复杂度略高于宽范围自相关函数法，而远低于宽范围LR算法。通过仿真比较，改进算法对低信噪比（SNR）环境（3-6dB）中的信号具有良好且稳定的估计性能。保证数据传输的实时性和可靠性；令节点在不工作期间进入睡眠状态，以保存能量.这些特点很适合无线传感网中的节能要求.
上传时间： 2022-07-23
上传用户：d1997wayne
