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.