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标题: [原创]全球三大3G标准的技术性比较分析  [查看完整版帖子] [打印本页]
时间:  2008-1-3 16:15
作者: ykd999     标题: [原创]全球三大3G标准的技术性比较分析

<p class="MsoNormal" align="left" style="MARGIN: 4.5pt 2.25pt 0pt; TEXT-INDENT: 22.5pt; LINE-HEIGHT: 15pt; TEXT-ALIGN: left; mso-pagination: widow-orphan;"><span style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">目前，中国的<span lang="EN-US">3G</span>即将进入商用化应用阶段，对技术标准的取舍选择也成为移动运营商要仔细考虑的问题，因此有必要对这三种主流技术标准进行比较分析。 </span><span lang="EN-US" style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;"><p></p></span></p><p class="MsoNormal" align="left" style="MARGIN: 4.5pt 2.25pt 0pt; TEXT-INDENT: 22.5pt; LINE-HEIGHT: 15pt; TEXT-ALIGN: left; mso-pagination: widow-orphan;"><span style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">三种主流的<span lang="EN-US">3G</span>技术标准<span lang="EN-US">--WCDMA</span>、<span lang="EN-US">cdma2000</span>和<span lang="EN-US">TD-SCDMA</span>，在技术上各有千秋，从目前的情况来看，不会出现哪种标准“一统江湖”的局面，而至于谁能在<span lang="EN-US">3G</span>时代占据更大的市场份额，关键是看哪个技术标准更符合市场需求和竞争的需要。<span lang="EN-US">
                                <p></p></span></span></p><p class="MsoNormal" align="left" style="MARGIN: 4.5pt 2.25pt 0pt; TEXT-INDENT: 22.5pt; LINE-HEIGHT: 15pt; TEXT-ALIGN: left; mso-pagination: widow-orphan;"><span style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">而需要注意的是，虽然<span lang="EN-US">cdma2000</span>、<span lang="EN-US">WCDMA</span>和<span lang="EN-US">TD-SCDMA</span>同属<span lang="EN-US">3G</span>的主流技术标准，但是仍然可以将其分为两类：<span lang="EN-US">cdma2000</span>、<span lang="EN-US">WCDMA</span>并作一类，<span lang="EN-US">TD-SCDMA</span>则和前两者分开讨论。之所以可以这样做，是因为在技术上<span lang="EN-US">cdma2000</span>和<span lang="EN-US">WCDMA</span>是<span lang="EN-US">FDD</span>的标准，而<span lang="EN-US">TD-SCDMA</span>则是一个<span lang="EN-US">TDD</span>标准。<span lang="EN-US">(</span>彻底调查<span lang="EN-US">) <p></p></span></span></p><p class="MsoNormal" align="left" style="MARGIN: 4.5pt 2.25pt 0pt; TEXT-INDENT: 22.5pt; LINE-HEIGHT: 15pt; TEXT-ALIGN: left; mso-pagination: widow-orphan;"><p class="MsoNormal" align="left" style="MARGIN: 4.5pt 2.25pt 0pt; TEXT-INDENT: 22.5pt; LINE-HEIGHT: 15pt; TEXT-ALIGN: left; mso-pagination: widow-orphan;"><span style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;"><span lang="EN-US"><p></p></span></span></p><span style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">主流<span lang="EN-US">3G</span>标准概要<span lang="EN-US">
                                <p></p></span></span></p><p class="MsoNormal" align="left" style="MARGIN: 4.5pt 2.25pt 0pt; TEXT-INDENT: 22.5pt; LINE-HEIGHT: 15pt; TEXT-ALIGN: left; mso-pagination: widow-orphan;"><span lang="EN-US" style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">1. cdma2000 <p></p></span></p><p class="MsoNormal" align="left" style="MARGIN: 4.5pt 2.25pt 0pt; TEXT-INDENT: 22.5pt; LINE-HEIGHT: 15pt; TEXT-ALIGN: left; mso-pagination: widow-orphan;"><span lang="EN-US" style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">cdma2000</span><span style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">是从<span lang="EN-US">cdmaOne</span>演进而来的第三代移动通信技术。事实上，<span lang="EN-US">cdma2000</span>标准是一个体系结构，称为<span lang="EN-US">cdma2000 family</span>，它同样还包含一系列的子标准。其技术特点如下：<span lang="EN-US">
                                <p></p></span></span></p><p class="MsoNormal" align="left" style="MARGIN: 4.5pt 2.25pt 0pt; TEXT-INDENT: 22.5pt; LINE-HEIGHT: 15pt; TEXT-ALIGN: left; mso-pagination: widow-orphan;"><span style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">前反向同时采用导频辅助相干解调<span lang="EN-US">;</span>在扩频码选择采用相同<span lang="EN-US">M</span>序列，通过不同的相位偏置区分不同的小区和用户<span lang="EN-US">;</span>射频带宽从<span lang="EN-US">1.25MHz</span>到<span lang="EN-US">20MHz</span>可调<span lang="EN-US">;</span>快速前向和反向功率控制<span lang="EN-US">;</span>下行信道中采用公共连续导频方式进行相干检测，提高系统容量<span lang="EN-US">;</span>在下行信道传输中，定义直扩和多载波传输两种方式，码片速率分别为<span lang="EN-US">3.6864Mcps</span>和<span lang="EN-US">1.22Mcps</span>，多载波方式能很好地兼容<span lang="EN-US">IS-95</span>网络<span lang="EN-US">;</span>支持<span lang="EN-US">F-QPCH</span>，可延长手机待机时间<span lang="EN-US">;</span>核心网络给予<span lang="EN-US">ANSI-41</span>网络的演进，并保持与<span lang="EN-US">ANSI-41</span>网络的兼容性<span lang="EN-US">;</span>支持软切换和更软切换<span lang="EN-US">;</span>设计了两类码复用业务信道，基本信道用于传送语音、信令和低速数据，是一个可变速率信道，补充信道用以传送高速率数据，在分组数据传送上应用了<span lang="EN-US">ALOHA</span>技术，改善传输性能<span lang="EN-US">;</span>在同步方式上<span lang="EN-US">cdma2000</span>与<span lang="EN-US">IS-95</span>相同，基站间同步采用<span lang="EN-US">GPS</span>方式。<span lang="EN-US">
                                <p></p></span></span></p><p class="MsoNormal" align="left" style="MARGIN: 4.5pt 2.25pt 0pt; TEXT-INDENT: 22.5pt; LINE-HEIGHT: 15pt; TEXT-ALIGN: left; mso-pagination: widow-orphan;"><span lang="EN-US" style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">cdma2000</span><span style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">的发起者主要以美国和韩国为主的以<span lang="EN-US">IS-95 CDMA</span>为标准的制造商和运营公司，<span lang="EN-US">cdma2000</span>继承了<span lang="EN-US">IS-95</span>窄带<span lang="EN-US">CDMA</span>系统的技术特点，网络运营商同样可以在窄带<span lang="EN-US">CDMA</span>网络中更换或增加部分网络设备过渡到<span lang="EN-US">3G</span>。<span lang="EN-US">
                                <p></p></span></span></p><p class="MsoNormal" align="left" style="MARGIN: 4.5pt 2.25pt 0pt; TEXT-INDENT: 22.5pt; LINE-HEIGHT: 15pt; TEXT-ALIGN: left; mso-pagination: widow-orphan;"><span lang="EN-US" style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">2. WCDMA <p></p></span></p><p class="MsoNormal" align="left" style="MARGIN: 4.5pt 2.25pt 0pt; TEXT-INDENT: 22.5pt; LINE-HEIGHT: 15pt; TEXT-ALIGN: left; mso-pagination: widow-orphan;"><span lang="EN-US" style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">WCDMA</span><span style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">的主要技术指标是：支持高速数据传输<span lang="EN-US">(</span>慢速移动时<span lang="EN-US">384kb/s</span>，室内走动时<span lang="EN-US">2Mb/s)</span>，异步<span lang="EN-US">BS</span>，支持可变速传输，帧长<span lang="EN-US">10ms</span>，码片速率<span lang="EN-US">3.84Mb/s</span>。其主要特点如下：<span lang="EN-US">
                                <p></p></span></span></p><p class="MsoNormal" align="left" style="MARGIN: 4.5pt 2.25pt 0pt; TEXT-INDENT: 22.5pt; LINE-HEIGHT: 15pt; TEXT-ALIGN: left; mso-pagination: widow-orphan;"><span style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">基站同步方式：支持异步和同步的基站运行方式，组网方便、灵活<span lang="EN-US">;</span>调制方式：上行为<span lang="EN-US">BPSK</span>，下行为<span lang="EN-US">QPSK;</span>解调方式：导频辅助的相干解调<span lang="EN-US">;</span>接入方式：<span lang="EN-US">DS-CDMA</span>方式<span lang="EN-US">;</span>三种编码方式：在话音信道采用卷积码<span lang="EN-US">(R=1/3</span>，<span lang="EN-US">K=9)</span>进行内部编码和<span lang="EN-US">Veterbi</span>解码，在数据信道采用<span lang="EN-US">ReedSolomon</span>编码，在控制信道采用卷积码<span lang="EN-US">(R=1/2</span>，<span lang="EN-US">K=9)</span>进行内部编码和<span lang="EN-US">Veterbi</span>解码<span lang="EN-US">;</span>适应多种速率的传输，可灵活地提供多种业务，并根据不同的业务质量和业务速率分配不同的资源，同时对多速率、多媒体的业务可通过改变扩频比<span lang="EN-US">(</span>对于低速率的<span lang="EN-US">32kb/s</span>、<span lang="EN-US">64kb/s</span>、<span lang="EN-US">128kb/s</span>的业务<span lang="EN-US">)</span>和多码并行传送<span lang="EN-US">(</span>对于高于<span lang="EN-US">128kb/s</span>的业务<span lang="EN-US">)</span>的方式来实现<span lang="EN-US">;</span>上、下行快速、高效的功率控制大大减少了系统的多址干扰，提高了系统容量，同时也降低了传输的功率<span lang="EN-US">;</span>核心网络基于<span lang="EN-US">GSM/GPRS</span>网络的演进，并保持与<span lang="EN-US">GSM/GPRS</span>网络的兼容性<span lang="EN-US">;BTS</span>之间无需同步因<span lang="EN-US">BS</span>可收发异步的<span lang="EN-US">N</span>码，即<span lang="EN-US">BS</span>可跟踪对方发出的<span lang="EN-US">N</span>码，同时<span lang="EN-US">MS</span>也可用额外的<span lang="EN-US">N</span>码进行捕获与跟踪，因此可获得同步，来支持越区切换及宏分集，而在<span lang="EN-US">BTS</span>之间无需进行同步<span lang="EN-US">;</span>支持软切换和更软切换，切换方式包括三种，即：扇区间软切换、小区间软切换和载频间硬切换。<span lang="EN-US">
                                <p></p></span></span></p><p class="MsoNormal" align="left" style="MARGIN: 4.5pt 2.25pt 0pt; TEXT-INDENT: 22.5pt; LINE-HEIGHT: 15pt; TEXT-ALIGN: left; mso-pagination: widow-orphan;"><span lang="EN-US" style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">WCDMA</span><span style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">的发起者主要是欧洲和日本标准化组织和厂商，<span lang="EN-US">WCDMA</span>继承了第二代移动通信体制<span lang="EN-US">GSM</span>标准化程度高和开放性好的特点，标准化进展顺利，网络运营商可以通过在<span lang="EN-US">GSM</span>网络上引入<span lang="EN-US">GPRS</span>网络设备和新业务，培育数据业务消费群体，逐步过渡到<span lang="EN-US">3G</span>。<span lang="EN-US">
                                <p></p></span></span></p><p class="MsoNormal" align="left" style="MARGIN: 4.5pt 2.25pt 0pt; TEXT-INDENT: 22.5pt; LINE-HEIGHT: 15pt; TEXT-ALIGN: left; mso-pagination: widow-orphan;"><span lang="EN-US" style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">3. TD-SCDMA <p></p></span></p><p class="MsoNormal" align="left" style="MARGIN: 4.5pt 2.25pt 0pt; TEXT-INDENT: 22.5pt; LINE-HEIGHT: 15pt; TEXT-ALIGN: left; mso-pagination: widow-orphan;"><span lang="EN-US" style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">TD-SCDMA</span><span style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">较前两种技术标准略显稚嫩，其主要技术特点如下：<span lang="EN-US">
                                <p></p></span></span></p><p class="MsoNormal" align="left" style="MARGIN: 4.5pt 2.25pt 0pt; TEXT-INDENT: 22.5pt; LINE-HEIGHT: 15pt; TEXT-ALIGN: left; mso-pagination: widow-orphan;"><span style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">信号带宽为<span lang="EN-US">1.23MHz;</span>码片速率为<span lang="EN-US">1.28Mchip/s;</span>采用智能天线技术，提高了频谱效率<span lang="EN-US">;</span>采用同步<span lang="EN-US">CDMA</span>技术，降低上行用户间的干扰和保持时隙宽度<span lang="EN-US">;</span>接收机和发射机采用软件无线电技术<span lang="EN-US">;</span>采用联合检测技术，降低多址干扰<span lang="EN-US">;</span>多时隙，具有上下行不对称信道分配能力，适应数据业务<span lang="EN-US">;</span>采用接力切换，降低掉话率，提高切换的效率<span lang="EN-US">;</span>语音编码：<span lang="EN-US">AMR</span>与<span lang="EN-US">GSM</span>兼容<span lang="EN-US">;</span>核心网络基于<span lang="EN-US">GSM/GPRS</span>网络的演进，并保持与它们的兼容性<span lang="EN-US">;</span>基站间采用<span lang="EN-US">GPS</span>或者网络同步方式，降低基站间干扰。<span lang="EN-US">
                                <p></p></span></span></p><p class="MsoNormal" align="left" style="MARGIN: 4.5pt 2.25pt 0pt; TEXT-INDENT: 22.5pt; LINE-HEIGHT: 15pt; TEXT-ALIGN: left; mso-pagination: widow-orphan;"><span lang="EN-US" style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">TD-SCDMA</span><span style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">目前主要是西门子公司和中国大唐集团在开发，较前两个技术标准而言，对<span lang="EN-US">TD-SCDMA</span>进行大力支持和结成产业联盟的企业还比较少。<span lang="EN-US">
                                <p></p></span></span></p><p class="MsoNormal" align="left" style="MARGIN: 4.5pt 2.25pt 0pt; TEXT-INDENT: 22.5pt; LINE-HEIGHT: 15pt; TEXT-ALIGN: left; mso-pagination: widow-orphan;"><span style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">三种主流标准的比较<span lang="EN-US">
                                <p></p></span></span></p><p class="MsoNormal" align="left" style="MARGIN: 4.5pt 2.25pt 0pt; TEXT-INDENT: 22.5pt; LINE-HEIGHT: 15pt; TEXT-ALIGN: left; mso-pagination: widow-orphan;"><span style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">虽然<span lang="EN-US">cdma2000</span>、<span lang="EN-US">WCDMA</span>和<span lang="EN-US">TD-SCDMA</span>同属<span lang="EN-US">3G</span>的主流技术标准，但是仍然可以将其分为两类：<span lang="EN-US">cdma2000</span>、<span lang="EN-US">WCDMA</span>并作一类，<span lang="EN-US">TD-SCDMA</span>则和前两者分开讨论。之所以可以这样做，是因为在技术上<span lang="EN-US">cdma2000</span>和<span lang="EN-US">WCDMA</span>是<span lang="EN-US">FDD</span>的标准，而<span lang="EN-US">TD-SCDMA</span>则是一个<span lang="EN-US">TDD</span>标准。<span lang="EN-US">
                                <p></p></span></span></p><p class="MsoNormal" align="left" style="MARGIN: 4.5pt 2.25pt 0pt; TEXT-INDENT: 22.5pt; LINE-HEIGHT: 15pt; TEXT-ALIGN: left; mso-pagination: widow-orphan;"><span lang="EN-US" style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">1. WCDMA</span><span style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">与<span lang="EN-US">cdma2000 <p></p></span></span></p><p class="MsoNormal" align="left" style="MARGIN: 4.5pt 2.25pt 0pt; TEXT-INDENT: 22.5pt; LINE-HEIGHT: 15pt; TEXT-ALIGN: left; mso-pagination: widow-orphan;"><span lang="EN-US" style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">WCDMA</span><span style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">和<span lang="EN-US">cdma2000</span>都满足<span lang="EN-US">IMT-2000</span>提出的全部技术要求，包括支持高比特率多媒体业务、分组数据和<span lang="EN-US">IP</span>接入等。这两种系统的无线传输技术均基于<span lang="EN-US">DS-CDMA</span>作为多用户接入技术，单就技术来说，<span lang="EN-US">WCDMA</span>和<span lang="EN-US">cdma2000</span>在技术先进性和发展成熟度上各具优势，但总体来看，<span lang="EN-US">WCDMA</span>似乎更胜一筹，以下是<span lang="EN-US">WCDMA</span>相对<span lang="EN-US">cdma2000</span>的一些优势所在：<span lang="EN-US">
                                <p></p></span></span></p><p class="MsoNormal" align="left" style="MARGIN: 4.5pt 2.25pt 0pt; TEXT-INDENT: 22.5pt; LINE-HEIGHT: 15pt; TEXT-ALIGN: left; mso-pagination: widow-orphan;"><span lang="EN-US" style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">(1) WCDMA</span><span style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">使用的带宽和码片速率<span lang="EN-US">(3.84Mcps)</span>是<span lang="EN-US">cdma2000 1x</span>演进家族的三倍以上，因而能提供更大的多路径分集、更高的中继增益和更小的信号开销。此外，更高的码片速率也改善了接收机解决多径效应的能力。<span lang="EN-US">
                                <p></p></span></span></p><p class="MsoNormal" align="left" style="MARGIN: 4.5pt 2.25pt 0pt; TEXT-INDENT: 22.5pt; LINE-HEIGHT: 15pt; TEXT-ALIGN: left; mso-pagination: widow-orphan;"><span lang="EN-US" style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">(2) WCDMA</span><span style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">在小区站点同步方面的设计是使用异步基站，而<span lang="EN-US">cdma2000</span>基站则通常通过<span lang="EN-US">GPS</span>实现同步，这将造成室内和城市小区<span lang="EN-US">(</span>采用室内天线<span lang="EN-US">)</span>部署的困难。<span lang="EN-US">
                                <p></p></span></span></p><p class="MsoNormal" align="left" style="MARGIN: 4.5pt 2.25pt 0pt; TEXT-INDENT: 22.5pt; LINE-HEIGHT: 15pt; TEXT-ALIGN: left; mso-pagination: widow-orphan;"><span lang="EN-US" style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">(3)</span><span style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">由于支持<span lang="EN-US">1xEV-DO</span>的<span lang="EN-US">TDM</span>接入系统采用共享时分复用下行链路，它具有固定时隙，因此<span lang="EN-US">cdma2000</span>物理层兼容性较差。<span lang="EN-US">
                                <p></p></span></span></p><p class="MsoNormal" align="left" style="MARGIN: 4.5pt 2.25pt 0pt; TEXT-INDENT: 22.5pt; LINE-HEIGHT: 15pt; TEXT-ALIGN: left; mso-pagination: widow-orphan;"><span lang="EN-US" style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">(4) WCDMA</span><span style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">较<span lang="EN-US">cdma2000</span>能够更加灵活地处理话音和数据混合业务。<span lang="EN-US">
                                <p></p></span></span></p><p class="MsoNormal" align="left" style="MARGIN: 4.5pt 2.25pt 0pt; TEXT-INDENT: 22.5pt; LINE-HEIGHT: 15pt; TEXT-ALIGN: left; mso-pagination: widow-orphan;"><span lang="EN-US" style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">(5) WCDMA</span><span style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">进行功率控制的频率几乎是<span lang="EN-US">cdma2000</span>的两倍，达到每秒<span lang="EN-US">1500</span>次<span lang="EN-US">(1.5kHz)</span>，因而能保证更好的信号质量，并支持更多的用户。<span lang="EN-US">
                                <p></p></span></span></p><p class="MsoNormal" align="left" style="MARGIN: 4.5pt 2.25pt 0pt; TEXT-INDENT: 22.5pt; LINE-HEIGHT: 15pt; TEXT-ALIGN: left; mso-pagination: widow-orphan;"><span lang="EN-US" style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">(6) cdma2000</span><span style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">的导频信道大约需要下行链路总传输功率的<span lang="EN-US">20%</span>，相比之下<span lang="EN-US">WCDMA</span>只需要约<span lang="EN-US">10%</span>，因而可以节省更多的公用信道的开销。<span lang="EN-US">
                                <p></p></span></span></p><p class="MsoNormal" align="left" style="MARGIN: 4.5pt 2.25pt 0pt; TEXT-INDENT: 22.5pt; LINE-HEIGHT: 15pt; TEXT-ALIGN: left; mso-pagination: widow-orphan;"><span lang="EN-US" style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">(7)</span><span style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">为支持基于<span lang="EN-US">GSM</span>的<span lang="EN-US">GPRS</span>业务而部署的所有业务<span lang="EN-US">(</span>如计费、安全、漫游等<span lang="EN-US">)</span>也支持<span lang="EN-US">WCDMA</span>业务，而为了完善新的数据<span lang="EN-US">/</span>话音网络，<span lang="EN-US">cdma2000 1x</span>必须添加额外的网元或进行功能的升级。<span lang="EN-US">
                                <p></p></span></span></p><p class="MsoNormal" align="left" style="MARGIN: 4.5pt 2.25pt 0pt; TEXT-INDENT: 22.5pt; LINE-HEIGHT: 15pt; TEXT-ALIGN: left; mso-pagination: widow-orphan;"><span lang="EN-US" style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">(8)</span><span style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">在混合话音和数据流量方面，<span lang="EN-US">WCDMA</span>的系统性能比<span lang="EN-US">cdma2000</span>也表现得更加出色。<span lang="EN-US">
                                <p></p></span></span></p><p class="MsoNormal" align="left" style="MARGIN: 4.5pt 2.25pt 0pt; TEXT-INDENT: 22.5pt; LINE-HEIGHT: 15pt; TEXT-ALIGN: left; mso-pagination: widow-orphan;"><span style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">因此，从技术的角度来讲，<span lang="EN-US">WCDMA</span>具备一定优势，各家电信企业也因此更加倾向于采用该标准。<span lang="EN-US">
                                <p></p></span></span></p><p class="MsoNormal" align="left" style="MARGIN: 4.5pt 2.25pt 0pt; TEXT-INDENT: 22.5pt; LINE-HEIGHT: 15pt; TEXT-ALIGN: left; mso-pagination: widow-orphan;"><span style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">另外，在传统网络基础和市场推广上，<span lang="EN-US">WCDMA</span>占据着更大的优势。由于全球移动系统有<span lang="EN-US">85%</span>都在用的<span lang="EN-US">GSM</span>系统，而<span lang="EN-US">GSM</span>向<span lang="EN-US">3G</span>过渡的最佳途径就是历经<span lang="EN-US">GPRS</span>演进到<span lang="EN-US">WCDMA</span>，所以传统网络上的绝对优势使得<span lang="EN-US">cdma2000</span>难以对<span lang="EN-US">WCDMA</span>望其项背。<span lang="EN-US">
                                <p></p></span></span></p><p class="MsoNormal" align="left" style="MARGIN: 4.5pt 2.25pt 0pt; TEXT-INDENT: 22.5pt; LINE-HEIGHT: 15pt; TEXT-ALIGN: left; mso-pagination: widow-orphan;"><span lang="EN-US" style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">2. TD-SCDMA <p></p></span></p><p class="MsoNormal" align="left" style="MARGIN: 4.5pt 2.25pt 0pt; TEXT-INDENT: 22.5pt; LINE-HEIGHT: 15pt; TEXT-ALIGN: left; mso-pagination: widow-orphan;"><span lang="EN-US" style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">TD-SCDMA</span><span style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">与<span lang="EN-US">WCDMA</span>和<span lang="EN-US">cdma2000</span>相比，具有如下的特点和优势：<span lang="EN-US">
                                <p></p></span></span></p><p class="MsoNormal" align="left" style="MARGIN: 4.5pt 2.25pt 0pt; TEXT-INDENT: 22.5pt; LINE-HEIGHT: 15pt; TEXT-ALIGN: left; mso-pagination: widow-orphan;"><span lang="EN-US" style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">(1)</span><span style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">频谱利用率高：<span lang="EN-US">TD-SCDMA</span>采用<span lang="EN-US">TDD</span>方式和<span lang="EN-US">CDMA</span>和<span lang="EN-US">TDMA</span>的多址技术，在传输中很容易针对不同类型的业务设置上、下行链路转换点，因而可以使总的频谱效率更高。<span lang="EN-US">
                                <p></p></span></span></p><p class="MsoNormal" align="left" style="MARGIN: 4.5pt 2.25pt 0pt; TEXT-INDENT: 22.5pt; LINE-HEIGHT: 15pt; TEXT-ALIGN: left; mso-pagination: widow-orphan;"><span lang="EN-US" style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">(2)</span><span style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">支持多种通信接口：<span lang="EN-US">TD-SCDMA</span>同时满足<span lang="EN-US">Iub</span>、<span lang="EN-US">A</span>、<span lang="EN-US">Gb</span>、<span lang="EN-US">Iu</span>、<span lang="EN-US">IuR</span>多种接口要求，基站子系统既可作为<span lang="EN-US">2G</span>和<span lang="EN-US">2.5G</span>的<span lang="EN-US">GSM</span>基站的扩容，又可作为<span lang="EN-US">3G</span>网中的基站子系统，能同时兼顾现在的需求和未来长远的发展。<span lang="EN-US">
                                <p></p></span></span></p><p class="MsoNormal" align="left" style="MARGIN: 4.5pt 2.25pt 0pt; TEXT-INDENT: 22.5pt; LINE-HEIGHT: 15pt; TEXT-ALIGN: left; mso-pagination: widow-orphan;"><span lang="EN-US" style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">(3)</span><span style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">频谱灵活性强：<span lang="EN-US">TD-SCDMA</span>第三代移动通信系统频谱灵活性强，仅需单一<span lang="EN-US">1.6M</span>的频带就可提供速率达<span lang="EN-US">2M</span>的<span lang="EN-US">3G</span>业务需求，而且非常适合非对称业务的传输。<span lang="EN-US">
                                <p></p></span></span></p><p class="MsoNormal" align="left" style="MARGIN: 4.5pt 2.25pt 0pt; TEXT-INDENT: 22.5pt; LINE-HEIGHT: 15pt; TEXT-ALIGN: left; mso-pagination: widow-orphan;"><span lang="EN-US" style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">(4)</span><span style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">系统性能稳定：<span lang="EN-US">TD-SCDMA</span>收发在同一频段上，上行链路和下行链路的无线环境一致性很好，更适合使用新兴的<span lang="EN-US">"</span>智能天线<span lang="EN-US">"</span>技术；利用了<span lang="EN-US">CDMA</span>和<span lang="EN-US">TDMA</span>结合的多址方式，更利于联合检测技术的采用，这些技术都能减少了干扰，提高系统的性能稳定性。<span lang="EN-US">
                                <p></p></span></span></p><p class="MsoNormal" align="left" style="MARGIN: 4.5pt 2.25pt 0pt; TEXT-INDENT: 22.5pt; LINE-HEIGHT: 15pt; TEXT-ALIGN: left; mso-pagination: widow-orphan;"><span lang="EN-US" style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">(5)</span><span style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">与传统系统兼容性好：<span lang="EN-US">TD-SCDMA</span>支持现存的覆盖结构，信令协议可以后向兼容，网络不必引入新的呼叫模式，能够实现从现存的通信系统到下一代移动通信系统的平滑过渡。<span lang="EN-US">
                                <p></p></span></span></p><p class="MsoNormal" align="left" style="MARGIN: 4.5pt 2.25pt 0pt; TEXT-INDENT: 22.5pt; LINE-HEIGHT: 15pt; TEXT-ALIGN: left; mso-pagination: widow-orphan;"><span lang="EN-US" style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">(6)</span><span style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">系统设备成本低<span lang="EN-US">:TD-SCDMA</span>上下行工作于同一频率，对称的电波传播特性使之便于利用智能天线等新技术，这也可达到降低成本的目的<span lang="EN-US">;</span>在无线基站方面，<span lang="EN-US">TD-SCDMA</span>的设备成本也比较低。<span lang="EN-US">
                                <p></p></span></span></p><p class="MsoNormal" align="left" style="MARGIN: 4.5pt 2.25pt 0pt; TEXT-INDENT: 22.5pt; LINE-HEIGHT: 15pt; TEXT-ALIGN: left; mso-pagination: widow-orphan;"><span lang="EN-US" style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">(7)</span><span style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">支持与传统系统间的切换功能<span lang="EN-US">:TD-SCDMA</span>技术支持多载波直接扩频系统，可以再利用现有的框架设备、小区规划、操作系统、账单系统等，在所有环境下支持对称或不对称的数据速率。<span lang="EN-US">
                                <p></p></span></span></p><p class="MsoNormal" align="left" style="MARGIN: 4.5pt 2.25pt 0pt; TEXT-INDENT: 22.5pt; LINE-HEIGHT: 15pt; TEXT-ALIGN: left; mso-pagination: widow-orphan;"><span style="COLOR: #333333; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt;">当然，与前两种标准相比，尤其是与<span lang="EN-US">WCDMA</span>比起来，<span lang="EN-US">TD-SCDMA</span>也有“尚显稚嫩”的地方。比如，在对<span lang="EN-US">CDMA</span>技术的利用方面，<span lang="EN-US">TD-SCDMA</span>因要与<span lang="EN-US">GSM</span>的小区兼容，小区复用系数为<span lang="EN-US">3</span>，降低了频谱利用率。又因为<span lang="EN-US">TD-SCDMA</span>频带宽度窄，不能充分利用多径，降低了系统效率，实现软切换和软容量能力较困难。另外，<span lang="EN-US">TD-SCDMA</span>系统要精确定时，小区间保持同步，对定时系统要求高。而<span lang="EN-US">WCDMA</span>则不需要小区间同步，可适应室内、室外，甚至地铁等不同的环境的应用。另外，<span lang="EN-US">WCDMA</span>对移动性的支持更加优质，适合宏蜂窝、蜂窝、微蜂窝组网，而<span lang="EN-US">TD-SCDMA</span>只适合微蜂窝，对高速移动的支持也较差。尤其是在从<span lang="EN-US">GSM</span>网向<span lang="EN-US">3G</span>的过渡过程中，<span lang="EN-US">WCDMA</span>的优势更加明显。因此，从目前的情况来看，<span lang="EN-US">TD-SCDMA</span>和<span lang="EN-US">WCDMA</span>虽然各具优势，但<span lang="EN-US">WCDMA</span>更应成为<span lang="EN-US">3G</span>过渡的主流标准。<span lang="EN-US">
                                <p></p></span></span></p>
时间:  2008-1-3 16:32
作者: 服务生

基本常识啊.
时间:  2008-1-3 16:52
作者: bestfly

是不是真的原创？
时间:  2008-1-3 17:00
作者: haolong153

新知识，谢谢
时间:  2008-1-3 17:16
作者: lily6189

了解
时间:  2008-1-4 13:55
作者: 無智

对我来说是新知识，但是感觉好象是基本概念！顶，谢谢！



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