3G科普之W-CDMA

W-CDMA
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Wideband Code Division Multiple Access 宽带CDMA) 是一种3G蜂窝网络。WCDMA UMTS使用的部分协议与2G GSM 标准一致。
具体一点来说，W-CDMA是一种利用码分多址复用(或者CDMA 通用 复用技术，不是指CDMA标准)方法的宽带扩频3G移动通信空中接口。

历史概要

历史上，欧洲电信标准委员会 (ETSI) 在 GSM 之后就开始研究其 3G 标准，其中有几种备选方案是基于直接序列扩频CDMA的，而日本的第三代研究也是使用宽带CDMA技术的，其后，以二者为主导进行融合，在3GPP组织中发展成了第三代移动通信系统UMTS，并提交给国际电信联盟(ITU)。
国际电信联盟最终接受WCDMA作为IMT-2000 3G标准的一部分。

误解

名字跟CDMA很相近，同时WCDMA跟CDMA关系也很微妙。两者都基于码分多址技术，都使用了美国高通（Qualcomm）的部分专利技术。一般认为WCDMA的提出是部分厂商为了绕开专利陷阱而开发的，其方案已经尽可能地避开高通专利。

在移动电话领域，术语 CDMA 可以代指码分多址扩频复用技术，也可以指美国高通（Qualcomm）开发的包括IS-95/CDMA1X和CDMA2000(IS-2000)的CDMA标准族。

在Qualcomm为IS-95协议使用它之前，CDMA复用技术已经存在了很长时间。然而，由于采用CDMA复用方法是IS-95协议区别于当时的GSM（采用TDMA）等其它协议的主要特征，现在通常将该协议也称为CDMA。

WCDMA 也使用CDMA的复用技术而且它跟Qualcomm的标准也很相似。但是WCDMA不仅仅是复用标准。它是一个详细的定义移动电话怎样跟基站通讯，信号怎样调制，数据帧怎么构建等的完整的规范集。

总之:

* 术语CDMA在移动通讯领域通常特指Qualcomm开发的CDMA标准族。它们定义了一组移动通讯协议。
* CDMA作为复用技术，既用于W-CDMA空中接口协议，也用于Qualcomm的CDMA协议。
* W-CDMA专指在IMT-2000中定义的移动电话协议。
* W-CDMA协议与Qualcomm开发的CDMA无关。
* CDMA标准族(IS-95/cdmaOne和CDMA2000)不兼容W-CDMA标准族。

当前状况

2001年，日本NTT DoCoMo公司的FOMA是世界上第一个商业运营W-CDMA服务。 FOMA不兼容UMTS。

J-Phone 日本电话(现沃达丰)已经继推出基于W-CDMA服务后，声称“沃达丰全球标准”兼容UMTS (尽管2004年时还有争议)。

2003年初，和记黄埔 逐步在全球运营他们的UMTS网络(简称3，参见en:3)。

大多数欧洲GSM运营商计划未来某个时间推出UMTS服务，尽管有几个已经把此服务提到日程上来，有一些甚至从2003年底就开始运营UMTS网络。

沃达丰于2004年2月在欧洲多个UMTS网络投入运行。沃达丰还打算在其他国家（包括澳大利亚及新西兰）建设UMTS网络。

AT&T 无线 (现属于Cingular Wireless) 在一些城市开通了UMTS。尽管因为公司兼并使得网络建设进度被延迟，但Cingular已宣布计划在2005年与HSDPA一起部署W-CDMA。

TeliaSonera于2004年10月13日开始在芬兰提供384kbps速率的W-CDMA服务。服务只是在主要城市可用。通讯费率大约2美元每兆字节。

产品认证

* GCF (Global Certification Forum)：现时是世界主要的2G及3G认证机构。
* PTCRB: 在北美为GSM移动设备（ME）类型认证提供框架。

技术

W-CDMA可以使用非成对或者成对频段，虽然所有当前W-CDMA设备（例如FOMA and UMTS）使用两个5MHz频段，一个用于上行一个用于下行。更多信息请参看扩频。

与其他标准比较

* 最初CDMA2000计划使用多个1.25MHz载波，但后来放弃了，而WCDMA则使用单一5MHz带宽载波。
* 在ITU的IMT-2000标准中，WCDMA被看作CDMA直接序列扩频，而CDMA2000被称作"多载波CDMA"。
* WCDMA 标准族(例如FOMA、UMTS)与CDMA标准族(例如IS-95和CDMA2000)不一致。


W-CDMA
From Wikipedia, the free encyclopedia

W-CDMA (Wideband Code Division Multiple Access) is a type of 3G cellular network. W-CDMA is the technology behind the 3G UMTS standard and is allied with the 2G GSM standard with the International Telecommunication Union - ITU.

More technically, W-CDMA is a wideband spread-spectrum 3G mobile telecommunication air interface that utilizes code division multiple access (or CDMA the general multiplexing scheme, not to be confused with CDMA the US standard).

History

W-CDMA was developed by NTT DoCoMo as the air interface for their 3G network FOMA. Later NTT DoCoMo submitted the specification to the International Telecommunication Union (ITU) as a candidate for the international 3G standard known as IMT-2000. The ITU eventually accepted W-CDMA as part of the IMT-2000 family of 3G standards. Later, W-CDMA was selected as the air interface for UMTS, the 3G data part of GSM. Attempts were made to unify W-CDMA (3GPP) and CDMA-1X (3GPP2) standards in order to provide a single worldwide standard. However, divergent requirements resulted in the two incompatible standards being retained.

Features

Only key features are cited below.

* Supports two basic modes of duplex: FDD (frequency division duplex) and TDD (time division duplex) modes
* Employs coherent detection on uplink and downlink based on the use of pilot symbols
* Inter-cell asynchronous operation
* Variable mission: on a 10 ms frame basis
* Multicode transmission
* Adaptive power control based on SIR
* Multiuser detection and smart antennas can be used to increase capacity and coverage
* Multiple types of handoffs between different cells including soft handoff, softer handoff and hard handoff

Misconceptions

W-CDMA is based on the Direct Spread CDMA technique. Code Division Multiple Access has been developed by a number of companies, and in the US this is dominated by Qualcomm. However, the ITU standard is not a Qualcomm implementation, but one where Qualcomm has been invited to participate. Other standards, such as TD-SDMA/TD-CDMA, have been developed by Siemens and Chinese companies independent of both the ITU and Qualcomm and bears no relationship with the US technology other than the name others have assigned to it.

In the mobile phone world, the term CDMA can refer to either the Code Division Multiple Access spread spectrum multiplexing technique, or the CDMA family of standards developed by Qualcomm, including cdmaOne (IS-95) and CDMA2000 (IS-2000 and IS-856).

The CDMA multiplexing technique existed long before Qualcomm used it for its IS-95 protocol. However, this protocol is now widely referred to as "CDMA" for its principal characteristic of using the CDMA multiplexing scheme to share multiple connections divided by different codes (PN sequences) over the same spectrum channel, as opposed to other spectrum division schemes

Qualcomm was able to introduce the first mobile protocol relying upon the CDMA multiplexing technique, associating the multiplexing technique with the name of the protocol.

W-CDMA is used in 3G as a political compromise made by the more advanced non-US companies to allow the US to participate in the rollout of 3G services. Since it now is part of the International Telecommunication Union's standards it is part of a larger suite of standards. W-CDMA is a complete set of specifications, a detailed protocol that defines how a mobile phone communicates with the tower, how signals are modulated, how datagrams are structured, and system interfaces are specified allowing free competition on technology elements.

In summary:

* The term CDMA in the mobile world typically refers to the CDMA family of standards developed by Qualcomm. They are protocols, sets of defined specifications of mobile communications
* CDMA (the multiplexing technique) is used as the principle of the W-CDMA air interface protocol, as well as Qualcomm's CDMA protocols
* W-CDMA strictly refers to a mobile phone protocol with detailed specifications, as defined in IMT-2000
* The W-CDMA protocol was developed independently of the CDMA protocol developed by Qualcomm.
* The CDMA family of standards (including cdmaOne and CDMA2000) are not compatible with the W-CDMA family of standards that are based on ITU standards.

Implementations

The world's first commercial W-CDMA service, FOMA, was launched by NTT DoCoMo in Japan in 2001. FOMA is compatible with standard UMTS. But the effort for migrating the FOMA specifications to UMTS are indicated by Japan.

J-Phone Japan (now Vodafone) soon followed by launching their own W-CDMA based service, originally branded "Vodafone Global Standard" and claiming UMTS compatibility. The name of the service was changed to "Vodafone 3G" in December 2004.

Beginning in 2003, Hutchison Whampoa gradually launched their upstart UMTS networks.

Most countries have since the ITU approved of the 3G mobile service either "auctioned" the radio frequencies to the company willing to pay the most, or conducted a "beauty contest" - asking the various companies to present what they intend to commit to if awarded the licenses. This strategy has been criticised for aiming to drain the cash of operators to the brink of bankruptcy in order to honour their bids or proposals. Most of them have a time constraint for the rollout of the service - where a certain "coverage" must be achieved within a given date or the license will be revoked.

Vodafone launched several UMTS networks in Europe in February 2004. MobileOne of Singapore commercially launched its 3G (W-CDMA) services in February 2005. New Zealand in August 2005 and Australia in October 2005.

AT&T Wireless (now a part of Cingular Wireless) has deployed UMTS in several cities. Though advancements in its network deployment have been delayed due to the merger with Cingular, Cingular began offering HSDPA service in December 2005.

Rogers in Canada is currently trialing HSDPA on W-CDMA at 1900MHz and plan the launch the service commercial in Q3, 2006.

TeliaSonera opened W-CDMA service in Finland October 13th 2004 with speeds up to 384 kbit/s. Availability only in main cities. Pricing is approx. 2€/MB. SK Telecom and KTF, two largest mobile phone service providers in South Korea, have each started offering W-CDMA service in December 2003. Due to poor coverage and lack of choice in handhelds, the W-CDMA service has barely made a dent in the Korean market which was dominated by CDMA2000. By October 2006 both companies are covering more than 90 cities while SK Telecom has announced that it will provide nationwide coverage for its WCDMA network in order for it to offer SBSM (Single Band Single Mode) handsets by the first half of 2007. KT Freecel will thus cut funding to its CDMA2000 network development to the minimum.

In Norway, Telenor introduced W-CDMA in major cities by the end of 2004, while their competitor, NetCom, followed suit a few months later. Both operators have 98 % national coverage on EDGE, but Telenor has parallel WLAN roaming networks on GSM, where the UMTS service is competing with this. For this reason Telenor is dropping support of their WLAN service in Austria (2006).

Maxis Communications and Celcom, two mobile phone service providers in Malaysia, started offering W-CDMA services in 2005.

In Sweden, Telia introduced W-CDMA March 2004.

Technology

W-CDMA may use unpaired or paired spectrum, though the current implementations of W-CDMA (i.e. FOMA and UMTS) all use a pair of 5MHz spectrum, one for uplink and one for downlink. See Spread spectrum for more information. FOMA uses sixteen slots per radio frame, where as UMTS uses 15 slots per radio frame.

3G科普之CDMA2000

CDMA2000
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CDMA2000 是一个3G移动通讯标准,国际电信联盟ITU的IMT-2000标准认可的无线电接口，也是2G CDMA标准(IS-95, 标志 CDMA1X)的延伸。 根本的信令标准是IS-2000。 CDMA2000与另一个主要的3G标准W-CDMA不兼容。

CDMA2000是美国通讯行业协会 (TIA-USA) 的注册商标, 并不是一个象CDMA一样的通用术语。TIA也注册了他们的2G CDMA标准(AKA IS-95)对应CDMA1X。

CDMA2000有多个不同的类型。下面按照复杂度排列：

# 1 CDMA2000 1x
# 2 CDMA2000 1xRTT
# 3 CDMA2000 1xEV

* 3.1 当前部署情况

# 4 CDMA2000 3x

CDMA2000 1x
CDMA2000 1x 就是众所周知的3G 1X 或者1xRTT, 它是3G CDMA2000技术的核心。标志 1x习惯上指使用一对1.25MHz无线电信道的CDMA2000无线技术。
日本运行商KDDI的CDMA2000 1xEV-DO网络使用商标 "CDMA 1X WIN"，不过这只是用于市场促销罢了。

CDMA2000 1xRTT
CDMA2000 1xRTT (RTT－无线电传输技术) 是CDMA2000一个基础层,支持最高144kbps数据速率.尽管获得3G技术的官方资格，但是通常被认为是2.5G或者 2.75G技术，因为它的速率只是其他3G技术几分之一。另外它拥有双倍的语音容量较之之前的CDMA网络。

CDMA2000 1xEV
CDMA2000 1xEV (Evolution－发展)是CDMA2000 1x附加了高数据速率 (HDR) 能力。1xEV一般分成2个阶段：
CDMA2000 1xEV第一阶段， CDMA2000 1xEV-DO (Evolution-Data Only－发展－只是数据)在一个无线信道传送高速数据报文数据的情况下，支持下行(向前链路)数据速率最高3.1Mbps，上行(反向链路) 速率最高到1.8 Mbps。
CDMA2000 1xEV第二阶段， CDMA2000 1xEV-DV (Evolution-Data and Voice发展－数据和语音), 支持下行 (向前链路 数据速率最高3.1 Mbps，上行(反相链路)速率最高1.8 Mbps。1xEV-DV还能支持1x语音用户， 1xRTT数据用户和高速1xEV-DV 数据用户使用同一无线信道并行操作。

1xEV-DO已经开始商业化运营。欧洲市场稍微早于美国市场。 2004年夏捷克移动运营商 Eurotel开始运营sinceCDMA2000 1xEV-DO网络，他们提供的上行速率大约1Mbps。这项服务每月大约花费30欧元无流量限制。如果使用这项服务，你需要购买一个大约300欧元的 Gtran GPC-6420调制解调器。

当前部署情况
2004年1月, 北美Verizon Wireless宣布计划在全国范围部署1xEV-DO。
尽管有些运营商已经完成测试或者有限的试用,但是到2004年7月还没有一个商业化运营的1xEV-DV。 美国运营商 Sprint PCS已经宣布计划在他们已有的CDMA网络基础上部署1xEV-DV网络 。
由于可用的1xEV-DV设备延迟交货和来自美国其他正在部署3G网络的运营商的压力, Sprint 宣布，2004年6月计划广泛部署1xEV-DO.但是他们的长期1xEV-DV计划好像还不确定(尽管他们当前计划2006年部署EV-DV).
Qualcomm高通最近由于缺乏运营利润可能已经停止EV-DV的开发, 更可能是因为Sprint和Verizon都在使用EV-DO.

CDMA2000 3x
CDMA2000 3x利用一对3.75 MHz无线信道(i.e., 3 X 1.25 MHz)来实现高速数据速率。3X版本的CDMA2000有时被叫做多载波（Multi-Carrier或者MC），这一版本还没有部署正处在研究开发阶段。

CDMA2000
From Wikipedia, the free encyclopedia

CDMA2000 is a family of third-generation (3G) mobile telecommunications standards that use CDMA, a multiple access scheme for digital radio, to send voice, data, and signalling data (such as a dialed telephone number) between mobile phones and cell sites. It is the second generation of CDMA digital cellular.

CDMA (code division multiple access) is a mobile digital radio technology that transmits streams of bits and whose channels are divided using codes (PN sequences). CDMA permits many radios to share the same frequency channel. Unlike TDMA (time division multiple access), a different technique used in GSM and D-AMPS, all radios can be active all the time, because network capacity does not directly limit the number of active radios. Since larger numbers of phones can be served by smaller numbers of cell sites, CDMA-based standards have a significant economic advantage over TDMA-based standards, or the oldest cellular standards that used frequency division multiple access (FDMA).

CDMA2000 has a relatively long technical history, and remains compatible with the older CDMA telephony methods (such as cdmaOne) first developed by Qualcomm, a commercial company, and holder of several key international patents on the technology.

The CDMA2000 standards CDMA2000 1x, CDMA2000 1xEV-DO, and CDMA2000 1xEV-DV are approved radio interfaces for the ITU's IMT-2000 standard and a direct successor to 2G CDMA, IS-95 (cdmaOne). CDMA2000 is standardized by 3GPP2.

CDMA2000 is a registered trademark of the Telecommunications Industry Association (TIA-USA) in the United States, not a generic term like CDMA. (This is similar to how TIA has branded their 2G CDMA standard, IS-95, as cdmaOne.)

CDMA2000 is an incompatible competitor of the other major 3G standard UMTS. It is defined to operate at 400 MHz, 800 MHz, 900 MHz, 1700 MHz, 1800 MHz, 1900 MHz, and 2100 MHz.

Below are the different types of CDMA2000, in order of increasing complexity:

# 1 CDMA2000 1x
# 2 CDMA2000 3x
# 3 CDMA2000 1xEV-DO
# 4 CDMA2000 1xEV-DV

CDMA2000 1x

CDMA2000 1x, the core CDMA2000 wireless air interface standard, is known by many terms: 1x, 1xRTT, IS-2000, CDMA2000 1X, 1X, and cdma2000 (lowercase). The designation "1xRTT" (1 times Radio Transmission Technology) is used to identify the version of CDMA2000 radio technology that operates in a pair of 1.25-MHz radio channels (one times 1.25 MHz, as opposed to three times 1.25 MHz in 3xRTT). 1xRTT almost doubles voice capacity over IS-95 networks. Although capable of higher data rates, most deployments have limited the peak data rate to 144 kbit/s. While 1xRTT officially qualifies as 3G technology, 1xRTT is considered by some to be a 2.5G (or sometimes 2.75G) technology. This has allowed it to be deployed in 2G spectrum in some countries which limit 3G systems to certain bands.

The main differences between IS-95 and IS-2000 signaling are: 64 more traffic channels on the forward link that are orthogonal to the original set. Some changes were also made to the data link layer to accommodate the greater use of data services—IS-2000 has media and link access control protocols and QoS control. In IS-95, none of these were present, and the data link layer basically consisted of a "best effort delivery" RLP—this arrangement is still used for voice.

In the United States, Verizon Wireless, Sprint PCS, Alltel, and U.S. Cellular use 1x, also it is in use in Canada by Bell Mobility and TELUS Mobility, and in Mexico by Iusacell and Unefon.

In India, BSNL, Reliance and Tata Teleservices are major wireless services providers on CDMA 2000 1x.

In Indonesia, Mobile-8 is the major mobile wireless service provider on CDMA 2000 1x (with EVDO in Western Java). The other CDMA providers are fixed wireless (such as Bakrie Telkom, Telkom Flexi, and Indosat's Starone).
CDMA2000 3x

CDMA2000 3x utilizes a pair of 3.75-MHz radio channels (i.e., 3 X 1.25 MHz) to achieve higher data rates. The 3x version of CDMA2000 is sometimes referred to as Multi-Carrier or MC. The 3x version of CDMA2000 has not been deployed and is not under development at present.

CDMA2000 1xEV-DO

Main article: Evolution-Data Optimized

CDMA2000 1xEV-DO (1x Evolution-Data Optimized, originally 1x Evolution-Data Only), also referred to as 1xEV-DO, EV-DO, EVDO, or just DO, is an evolution of CDMA2000 1x with High Data Rate (HDR) capability added and where the forward link is time-division multiplexed. This 3G air interface standard is denoted as IS-856.

CDMA2000 1xEV-DO in its latest revision, Rev. A, supports downlink (forward link) data rates up to 3.1 Mbit/s and uplink (reverse link) data rates up to 1.8 Mbit/s in a radio channel dedicated to carrying high-speed packet data. 1xEV-DO Rev. A was first deployed in Japan and will be deployed in North America in 2006. The Rev. 0 that is currently deployed in North America has a peak downlink data rate of 2.5 Mbit/s and a peak uplink data rate of 154 kbit/s.

Verizon Wireless, Sprint Nextel Corporation, Bell Canada, and TELUS are in the midst of nationwide deployment of 1xEV-DO Rev. A in North America, and Alaska Communications Systems (ACS) is deploying 1xEV-DO in the main population centers of Alaska. Verizon Wireless currently uses its 1xEV-DO Rev. 0 network for its VCAST services, while Sprint Nextel Corporation currently uses its 1xEV-DO Rev. 0 network for its Power Vision services.

Japanese operator KDDI uses the brand "CDMA 1X WIN" for their CDMA2000 1xEV-DO network, but this is only in reference to its building on past marketing promotions.

South Korean Operator SK Telecom currently uses its 1xEV-DO Rev.0 network for its "june" brand , while KTF currently uses its 1xEV-DO Rev.0 network for its "fimm" brand services.

CDMA2000 1xEV-DV

CDMA2000 1xEV-DV (1x Evolution-Data/Voice), supports downlink (forward link) data rates up to 3.1 Mbit/s and uplink (reverse link) data rates of up to 1.8 Mbit/s. 1xEV-DV can also support concurrent operation of legacy 1x voice users, 1x data users, and high speed 1xEV-DV data users within the same radio channel.

In 2005, Qualcomm put the development of EV-DV on an indefinite halt, due to lack of carrier interest, mostly because both Verizon Wireless and Sprint are using EV-DO.