WCDMA导论 Introduction to WCDMA

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WCDMA导论 Introduction to WCDMA(中文5100字,英文3000字)
3.1 引言
本章介绍WCDMA 空中接口的基本原理,并且特别关注那些与GSM 和IS-95 不同的特
性。3.2 节介绍WCDMA 物理层的主要参数。3.3 节介绍扩频和解扩的概念,随后在3.4 节中
介绍多径无线信道和Rake 接收机。其他一些WCDMA 空中接口的关键组成部分——功率控
制、软切换和更软切换也将在本章中介绍。3.5 节阐述了功率控制的必要性及实现,3.6 节介
3.2 WCDMA 主要参数概括
在本节中,我们将介绍WCDMA 的主要系统参数,并对其中的大多数参数做出简要解释。
表3-1 概括了有关WCDMA 空中接口的主要参数。在此我们主要突出一些表征WCDMA 特
表3-1 WCDMA 的主要参数
多址接入方式            DS-CDMA
双工方式                频分双工/时分双工
基站同步                异步方式
码片速率                3.84Mchip/s
帧长                    10ms
业务复用                有不同服务质量要求的业务复用到一个连接中
多速率概念              可变的扩频因子和多码
检测                    使用导频符号或公共导频进行相关检测,多用户检测,智能天线 标准支持,应用时可选

Introduction to WCDMA
Peter Muszynski and Harri Holma
3.1 Introduction
This chapter introduces the principles of the WCDMA air interface. Special attention is
drawn to those features by which WCDMA differs from GSM and IS-95. The main
parameters of the WCDMA physical layer are introduced in Section 3.2. The concept of
spreading and despreading is described in Section 3.3, followed by a presentation of the
multipath radio channel and Rake receiver in Section 3.4. Other key elements of the
WCDMA air interface discussed in this chapter are power control and soft and softer
handovers. The need for power control and its implementation are described in Section 3.5,
and soft and softer handover in Section 3.6.
3.2 Summary of the Main Parameters in WCDMA
We present the main system design parameters of WCDMA in this section and give brief
explanations for most of them. Table 3.1 summarises the main parameters related to the
WCDMA air interface. Here we highlight some of the items that characterise WCDMA.
_ WCDMA is a wideband Direct-Sequence Code Division Multiple Access (DS-CDMA)
system, i.e. user information bits are spread over a wide bandwidth by multiplying the
user data with quasi-random bits (called chips) derived from CDMA spreading codes. In
order to support very high bit rates (up to 2 Mbps), the use of a variable spreading factor
and multicode connections is supported. An example of this arrangement is shown in
Figure 3.1.