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In 3G, the most prevalent technology was UMTS with CDMA-2000 in close contention. All radio access technologies have to solve the same problems: to divide the finite RF spectrum among multiple users as efficiently as possible. GSM uses TDMA and FDMA for user and cell separation. UMTS, IS-95 and CDMA-2000 use CDMA. WiMAX and LTE use OFDM.
With the evolution of CDMA to CDMA2000 and 1xRTT, the use of IS-95 CDMA Circuit Switched Data declined in favour of the faster data transmission speeds available with the newer technologies. Prior to CSD, data transmission over mobile phone systems was done by using a modem, either built into the phone or attached to it.
In a CDMA system, the same frequency can be used in every cell, because channelization is done using the pseudo-random codes. Reusing the same frequency in every cell eliminates the need for frequency planning in a CDMA system; however, planning of the different pseudo-random sequences must be done to ensure that the received signal from one ...
In Russia and some other countries, local carriers received licenses for 450 MHz frequency to provide CDMA mobile coverage area. Many GSM phones support three bands (900/1,800/1,900 MHz or 850/1,800/1,900 MHz) or four bands (850/900/1,800/1,900 MHz), and are usually referred to as tri-band and quad-band phones, or world phones; with such a ...
CDMA2000 is a family of 3G mobile technology standards for sending voice, data, and signaling data between mobile phones and cell sites. It is a backwards-compatible successor to second-generation cdmaOne (IS-95) set of standards and used especially in North America and South Korea, China, Japan, Australia and New Zealand.
Most 2G cellular systems, with the notable exception of IS-95, are based on TDMA. GSM, D-AMPS, PDC, iDEN, and PHS are examples of TDMA cellular systems.. In the GSM system, the synchronization of the mobile phones is achieved by sending timing advance commands from the base station which instruct the mobile phone to transmit earlier and by how much.
A security researcher has unveiled a decrypting method for phones that use the Global System for Mobile Communications (GSM). This means that if you are using a GSM cell phone, it has just gotten ...
These phones include combination of GSM and CDMA technology. They can be used as a GSM or CDMA phone according to the user's preference. These handsets are also called global phones. An example of this is the Samsung SCH-A790. These dual-mode handsets are compatible with both GSM and CDMA networks and are essentially two phones in one device.
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