CDMA：碼分多址 (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的縮寫 。 碼分多址是一種數字蜂窩技術，可顯示多址網絡。 各種無線電通信技術都將該技術用作對信道的訪問。 它通常用于移動通信。

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.

各種發射機可以在單個傳輸的信道上同時傳輸信息，該信道描述了對CDMA的多路訪問的含義。 在這種安排下，為不同的用戶分配了不同的CDMA碼，并且整個周期內，用戶可以無中斷地訪問整個帶寬。 它不限制用戶的頻率范圍，因為它在整個頻率范圍內發送，并且最有效地利用了可用的帶寬。 因此， CDMA使各種用戶能夠在用戶之間共享頻帶而不受到過多干擾。 在許多級別的手機上，它被用作一種訪問技術。

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.

在第二次世界大戰期間， CDMA技術由英語同盟開發，以保護他們的無線通信不被嚴格限制在指定的空間內。 當戰爭到達終點時，高通公司通過為這項技術申請了專利，使每個人都可以在商業上使用它。 1995年9月，和記電話公司在香港推出了第一個CDMA系統。

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用法 (Usage)

• The Global Positioning System (GPS) uses this system of technology.

  全球定位系統(GPS)使用此技術系統。

• Various mobile phone companies use this system e.g. Qualcomm standard IS-2000 also known as CDMA2000 use this system of technology.

  各種移動電話公司都使用該系統，例如，Qualcomm標準IS-2000(也稱為CDMA2000)使用該技術系統。

• In UMTS 3G mobile phone standard, W-CDMA is used.

  在UMTS 3G手機標準中，使用W-CDMA。

• In the OmniTRACS satellite system, CDMA has been used for transferring signals from one place to another.

  在OmniTRACS衛星系統中，CDMA已用于將信號從一個地方傳輸到另一個地方。

CDMA類型 (Types of CDMA)

• Synchronous CDMA (orthogonal codes)

  同步CDMA(正交碼)

• Asynchronous CDMA (pseudorandom codes)

  異步CDMA(偽隨機碼)

CDMA與GSM之間的差異 (Differences between CDMA and GSM)

Following are the crucial differences between CDMA and GSM,

以下是CDMA和GSM之間的關鍵區別 ，

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.

碼分多址	GSM
CDMA基于擴頻技術進行操作，該技術可充分利用可用帶寬。	GSM基于楔形頻譜進行操作。 它同時使用時分多址(TDMA)和頻分多址(FDMA)。
CDMA更安全。	GSM安全性較低。
CDMA在美國以及加拿大和日本的某些地區使用。 全球有24％的用戶僅使用CDMA。	GSM在210多個國家/地區中占全球網絡的80％以上。 全球76％的用戶使用GSM。
CDMA的數據傳輸速度更快。	GSM的數據傳輸速度較慢。
CDMA手機發出的輻射較少。	GSM手機連續發射波脈沖，并發射近28倍的輻射。

翻譯自: https://www.includehelp.com/dictionary/cdma-full-form.aspx