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.
標簽： Analog-Digital Precoding Hybrid
上傳時間： 2020-05-27
上傳用戶：shancjb
Mobile radio communications are evolving from pure telephony systems to multimedia platforms offering a variety of services ranging from simple file transfers and audio and video streaming, to interactive applications and positioning tasks. Naturally, these services have different constraints concerning data rate, delay, and reliability (quality-of-service (QoS)). Hence, future mobile radio systems have to provide a large flexibility and scal- ability to match these heterogeneous requirements.
標簽： Communications Wireless Channels MIMO over
上傳時間： 2020-06-01
上傳用戶：shancjb
In the present era, low observability is one of the critical requirements in aerospace sector, especially related to defense. The stealth technology essentially relates to shaping and usage of radar absorbing materials (RAM) or radar absorbing struc- tures (RAS). The performance of such radar cross section (RCS) reduction tech- niques is limited by the bandwidth constraints, payload requirements, and other structural issues. Moreover, with advancement of materials science, the structure geometry no longer remains key decisive factor toward stealth.
標簽： Fundamentals Design Radar of EM
上傳時間： 2020-06-06
上傳用戶：shancjb
This book is focused on designing and developing Representational State Transfer (REST) platforms in Rails. REST is the architectural style of the Web, consisting of a set of constraints that, applied to components, connectors, and data elements, constitute the wider distributed hypermedia system that we know today: the World Wide Web. There are a few good reasons why it makes more sense to build platforms instead of just products or applications. Platforms are like ecosystems interconnecting different applications, services, users, developers, and partners. Platforms foster innovation through the inputs of their direct collaborators. By providing application programming interfaces (APIs) and software development kits (SDKs), platforms are more customer driven.
標簽： Development Building RESTful Rails
上傳時間： 2020-06-06
上傳用戶：shancjb
This texts contemporary approach focuses on the concepts of linear control systems, rather than computational mechanics. Straightforward coverage includes an integrated treatment of both classical and modern control system methods. The text emphasizes design with discussions of problem formulation, design criteria, physical constraints, several design methods, and implementation of compensators.Discussions of topics not found in other texts--such as pole placement, model matching and robust tracking--add to the texts cutting-edge presentation. Students will appreciate the applications and discussions of practical aspects, including the leading problem in developing block diagrams, noise, disturbances, and plant perturbations. State feedback and state estimators are designed using state variable equations and transfer functions, offering a comparison of the two approaches. The incorporation of MATLAB throughout the text helps students to avoid time-consuming computation and concentrate on control system design and analysis
標簽： 控制系統
上傳時間： 2021-12-15
上傳用戶：
本文主要介紹如何在Wado設計套件中進行時序約束，原文出自 xilinx中文社區。1 Timing constraints in Vivado-UCF to xdcVivado軟件相比于sE的一大轉變就是約束文件，5E軟件支持的是UcF（User constraints file，而 Vivado軟件轉換到了XDc（Xilinx Design constraints）。XDC主要基于SDc（Synopsys Design constraints）標準，另外集成了Xinx的一些約束標準可以說這一轉變是xinx向業界標準的靠攏。Altera從 TimeQuest開始就一直使用SDc標準，這一改變，相信對于很多工程師來說是好事，兩個平臺之間的轉換會更加容易些。首先看一下業界標準SDc的原文介紹：Synopsys widely-used design constraints format, known as sDc, describes the design intent"and surrounding constraints for synthesis, clocking, timing, power, test and environmental and operating conditions. sDc has been in use and evolving for more than 20 years, making it the most popular and proven format for describing design constraints. Essentially all synthesized designs use SDc and numerous EDa companies have translators that can read and process sDc
標簽： vivado
上傳時間： 2022-03-26
上傳用戶：
