CDMA的完整形式是什么？

CDMA：码分多址 (CDMA: Code Division Multiple Access)

CDMA is an abbreviation of Code Division Multiple Access. Code Division Multiple Access is a digital cellular technology and displays a network of multiple accesses. The various radio communication technologies use this technique as access to channels. It is commonly used for the communication of mobile.

CDMA是Code Division Multiple Access的缩写 。 码分多址是一种数字蜂窝技术，可显示多址网络。各种无线电通信技术都将该技术用作对信道的访问。它通常用于移动通信。

The various transmitters can transmit information at the same time over a channel of single transmission which depicts the meaning of multiple access to CDMA. In this arrangement, different users are allotted for different CDMA codes and the whole period, the user can access the entire bandwidth without any interruption. It does not restrict the user's range of frequency, as it sends over the complete range of frequency and also makes the most effective use of bandwidth which is available. Therefore, CDMA enables various users to share a band of frequencies between users without excessive interference. On many levels of mobile phones, it is used as an access technique.

各种发射机可以在单个传输的信道上同时传输信息，该信道描述了对CDMA的多路访问的含义。在这种安排下，为不同的用户分配了不同的CDMA码，并且整个周期内，用户可以无中断地访问整个带宽。它不限制用户的频率范围，因为它在整个频率范围内发送，并且最有效地利用了可用的带宽。因此， CDMA使各种用户能够在用户之间共享频带而不受到过多干扰。在许多级别的手机上，它被用作一种访问技术。

During World War II, CDMA technology was developed by English confederate to safeguard their wireless communications from confining tightly into a specified space. When the war came to a finish point, Qualcomm by patenting this technology, made it accessible for everyone commercially. In 1995 September, the first CDMA system was introduced by Hutchison Telephone Co. in Hong Kong.

在第二次世界大战期间， CDMA技术由英语同盟开发，以保护他们的无线通信不被严格限制在指定的空间内。当战争到达终点时，高通公司通过为这项技术申请了专利，使每个人都可以在商业上使用它。 1995年9月，和记电话公司在香港推出了第一个CDMA系统。

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用法 (Usage)

The Global Positioning System (GPS) uses this system of technology.
全球定位系统(GPS)使用此技术系统。
Various mobile phone companies use this system e.g. Qualcomm standard IS-2000 also known as CDMA2000 use this system of technology.
各种移动电话公司都使用该系统，例如，Qualcomm标准IS-2000(也称为CDMA2000)使用该技术系统。
In UMTS 3G mobile phone standard, W-CDMA is used.
在UMTS 3G手机标准中，使用W-CDMA。
In the OmniTRACS satellite system, CDMA has been used for transferring signals from one place to another.
在OmniTRACS卫星系统中，CDMA已用于将信号从一个地方传输到另一个地方。

CDMA类型 (Types of CDMA)

Synchronous CDMA (orthogonal codes)
同步CDMA(正交码)
Asynchronous CDMA (pseudorandom codes)
异步CDMA(伪随机码)

CDMA与GSM之间的差异 (Differences between CDMA and GSM)

Following are the crucial differences between CDMA and GSM,

以下是CDMA和GSM之间的关键区别，

CDMA	GSM
CDMA operates based on spread-spectrum technology which makes the best use of available bandwidth.	GSM operates based on the wedge spectrum. it uses both time division multiple access (TDMA) and frequency division multiple access (FDMA).
CDMA is more secure.	GSM is less secure.
The use of CDMA is in the USA and some parts of Canada and Japan. 24% of users worldwide only use CDMA.	The use of GSM is over 80% of the world network in over 210 countries. 76% of the users worldwide use GSM.
CDMA has faster data transfer.	GSM has slower data transfer.
CDMA phones emit less radiation.	GSM phones emit wave pulses continuously and emit nearly 28 times more radiation.

码分多址	GSM
CDMA基于扩频技术进行操作，该技术可充分利用可用带宽。	GSM基于楔形频谱进行操作。它同时使用时分多址(TDMA)和频分多址(FDMA)。
CDMA更安全。	GSM安全性较低。
CDMA在美国以及加拿大和日本的某些地区使用。全球有24％的用户仅使用CDMA。	GSM在210多个国家/地区中占全球网络的80％以上。全球76％的用户使用GSM。
CDMA的数据传输速度更快。	GSM的数据传输速度较慢。
CDMA手机发出的辐射较少。	GSM手机连续发射波脉冲，并发射近28倍的辐射。