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Showing posts with label Knowledge. Show all posts
Showing posts with label Knowledge. Show all posts

Saturday, March 26, 2011

History and Advantages of CDMA Technology



CDMA (code division multiple access) is a multiple access technology, where each user uses a unique code contained in the access channel in the system. 

In CDMA, the information signal at the transmitter dicoding and dispersed with a bandwidth of 1.25 MHz (spread spectrum), then on the side of the repeater is decoding to obtain the required information signal. The experts agree that mobile phone technology sophistication far beyond GSM CDMA is now used by many mobile phone operators in Indonesia. CDMA tariffs will be far below the GSM because of its investment cost is very cheap. 



CDMA technology was initially used in military radio communication United States (U.S.), began in 1990 patent granted to Qualcomm, Inc.. and serve as a digital cellular standard in the U.S. since 1993. Therefore do not be surprised if this technology is very safe because it can not be duplicated (cloned). 


So this technology is very suitable for the use of telephone banking services, such as transfers, check balances, etc.. GSM is supported by the European countries more quickly soared to the number of users around the world which today has reached over 700 million. While the number of CDMA subscribers reached 120 million. GSM and CDMA variants with initial IS-95 A also appear at the same time in the early years of the 90s generation mobile phone technology is categorized in the 2nd (2G). 


Some of the advantages of CDMA-2000 (1X) when compared with GSM as follows: 

 
1. As military technology

CDMA is very resistant to weather disturbances and interference, therefore CDMA is very low noise resulting in excellent sound quality. Even in the rain very lebatpun sound quality is still within the limits of which can still be tolerated. 

2. CDMA can not be duplicated (cloned) 

Because every customer is given a different code (unique). These codes are very difficult to track because it is random. 

3. Very low coverage (1 / 100 GSM)  

CDMA mobile phone allows efficient in battery consumption, so it can operate longer to speak or stand by.

4. Capacity of CDMA subscribers per base station can reach 6000 (10 GSM).  

This is due to CDMA is more efficient in the use of frequencies. All CDMA base stations operating at the same frequency, so it does not require complex calculations in a configuration set-rasinya. The amount of capacity per BTS makes the investment costs incurred are very low. In addition, CDMA-2000 (1X) operating at 800 MHz frequency spectrum. This will create a broad base stations coverage far greater than GSM. So just need fewer base stations to cover the same areas when compared with GSM. 

5. CDMA-2000 (1X)  

Can send data at speeds up to 144 kbps, while GSM 9.6 Kbps. So that can support SMS, MMS, play games and download data via the Internet.

Differences Data Access GPRS - EDGE - 3G/UMTS - 3.5G/HSDPA



This article discusses a bit about the differences only four such data access (GPRS - EDGE - UMTS - HSDPA). Before there were four such data access, there are several other types of data access, the CSD (Circuit Switched Data).

GPRS (General Packet Radio Service): 

a technology used for sending and receiving data packets. GPRS is often called 2.5G technology. Facilities provided by the GPRS: e-mail, MMS (picture messages), browsing the Internet. In theory GPRS provide access speeds between 56kbps to 115kbps.

EDGE (Enhanced Data for Global Evolution):  

the development of GSM technology, the average has 3 times speed of GPRS speeds. EDGE access speed is theoretically about 384kbps. EDGE provides facilities like GPRS (e-mail, MMS, and browsing).

UMTS (Universal Mobile Telecommunications Service): 

Further development of EDGE. UMTS is often called third generation (3G). In addition to providing Internet access facilities (e-mail, MMS, and browsing), UMTS also provides video streaming, video conferencing, and video calling *). In theory UMTS access speeds around 480kbps.

HSDPA (High Speed ​​Downlink Packet Access)

is a further development of 3G data access. HSDPA is often referred to as generation 3.5 (3.5G) for HSDPA is still running on the 3G platform. In theory the same speed HSDPA data access, such as 480kbps, but it was definitely faster HSDPA. If not what good is creating faster HSDPA. The more exact the better new technologies.

All four data access over a modem implemented on mobile phone / cell phone, there is also a special modem that is used for connection.