commthu的专栏

支持2G/3G/4G/5G所有通信制式广播信道的解码，包括：GSM，CDMA，EVDO，WCDMA，TD-SCDMA，TD-LTE，FDD-LTE，5G-NR。

Fundamentals of DSL Technology Fundamentals of DSL Technology Fundamentals of DSL Technology

GSM and Personal Communications Handbook GSM and Personal Communications Handbook GSM and Personal Communications Handbook GSM and Personal Communications Handbook GSM and Personal Communications Handbook

This book is concerned with the description and analysis of the global second generation (2G) mobile radio systems: the Global System of Mobile Communications (GSM) and cdmaOne. A subsidiary goal is to examine how these two systems will evolve into third generation (3G) ones with their requirement to support multimedia mobile radio communications. The motivation for this book originated when we were asked to compare the capacities of GSM and, as cdmaOne was known then, IS-95. The multiple access method used by GSM is time division multiple access (TDMA), and this represented a significant change from the first generation (1G) analogue systems that operated with frequency division multiple access (FDMA). IS-95 had a more complex radio interface than GSM, employing code division multiple access (CDMA). Engineers at that time often held strong and somewhat uncompromising views regarding multiple access methods. We preferred CDMA from a spectral efficiency point of view, although that does not mean that CDMA should be deployed in preference to TDMA as there are many complex performance and economic factors to be considered when deciding on the type of system to select. GSM was deployed before cdmaOne and is the market leader, entrenched in many parts of the world. Its success is due to numerous factors: its advanced backbone network, the introduction of subscriber identitymodules (SIMs) that decoupled handsets from subscribers, its good security system, the low cost equipment due to open (i.e. public) interfaces, the relentless programme of evolution that has yielded substantial gains in spectral efficiency compared with the basic GSM system, and so on. cdmaOne started as a radio interface. It was a bold step to use CDMA at a time when few thought CDMA could work in a cellular environment. But it did so, acquiring the necessary backbone network, and became a global standard offering tough competition to GSM. It is also worthy of note that Europe, which had designed and promoted GSM, has opted for wideband CDMA for its third generation (3G) networks. Our cardinal objectives in this book are to present to the reader detailed descriptions

本书主要从GSM原理及网络优化的角度出发，首先通过对GSM移动通信系统的组成、优化流程、无线接口理论的介绍使得用户对GSM网络原理有了一定的理论基础。随后通过对呼叫处理过程的分析、信令协议的介绍，将GSM的BSS部分和NSS部分有机地结合起来，使得读者对移动台和网络针对各种通信需要的信令传输过程有了一个全面、深刻的认识，这一部分是GSM网络优化所必备的理论知识，对于初学者来说该部分确实有一定的深度和难度。本书最后较为详细地阐述了有关网络优化实践操作的相关知识，包括常用参数的优化调整、网络优化应注意的部分问题以及网络故障的处理，这一部分是GSM网络优化理论的应用与实践，通过大量实例的列举可以使读者对各种疑难的网络故障处理找到入手之处。

Lecture 1: Channel Capacity In this lecture we review the Shannon capacity of an additive white Gaussian noise channel, the capacity theorem and spectral efficiency and power efficiencies possible. • Lecture 2: MIMO Channel Capacity We then extend the capacity to parallel channels and study the optimal power distribution, which leads to the waterfilling theorem. Next the multiple-input multiple-ouput (MIMO) channel is considered and related to the parallel Gaussian channel via the singular value decomposition (SVD). Its capacity and equal power (symmetric) capacity are discussed. Finally the capacity fromula is extended to fading MIMO channels. • Lecture 3: Real-World MIMO channels We study different types of MIMO channels, their rank and capacity gain. Examples are studied by emulating the propagation environment of MIMO channels. It is argued and demonstrated that in the low signal-to-noise ratio regime, MIMO channels offers no capacity advantage over single point-to-point channels. • Lecture 4: Linear Multiantenna Processing We discuss linear processing for multiple-antenna channels and beam-forming. The multiple signal classification (MUSIC) algorithm is introduced as the predominant sub-space method for parameter identification. Projection beam-formers and minimum-mean square error (MMSE) beam-formers are then discussed as well as the minimum-variance distortionless beam-former. • Lecture

CDMA扩频通信原理，Viterbi 目录 第一章 引言 第二章 随机和伪随机信号的产生 第三章 伪随机信号的同步 第四章 多径和多址干扰下扩频信号的调制与解调 第五章 编码与交织 第六章 容量、覆盖及扩频多址网络的控制