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GSM uses TDMA and FDMA for user and cell separation. UMTS, IS-95 and CDMA-2000 use CDMA. WiMAX and LTE use OFDM. Time-division multiple access (TDMA) provides multiuser access by chopping up the channel into sequential time slices. Each user of the channel takes turns to transmit and receive signals.
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.
5G NR and related 5G standards, including 5G-Advanced An evolved IP Multimedia Subsystem (IMS) developed in an access independent manner 3GPP is a consortium with seven national or regional telecommunication standards organizations as primary members ("organizational partners") and a variety of other organizations as associate members ("market ...
[3] The North American Standards IS-54 and IS-136 were also second-generation (2G) mobile phone systems, known as (Digital AMPS) and used TDMA with three time slots in each 30 kHz channel, supporting 3 digitally compressed calls in the same spectrum as a single analog call in the previous AMPS standard. This was later changed to 6 half rate ...
An Android phone, showing that it is connected to a 5G network An Apple iPhone showing that it is connected to a 5G Network. In telecommunications, 5G is the fifth generation of cellular network technology, which mobile operators began deploying worldwide in 2019 as the successor to 4G. 5G is based on standards defined by the International Telecommunication Union under the IMT-2020 ...
However, reducing interference is a significant component in how GSM and other TDMA based mobile phone systems make better use of the available spectrum compared to older analog systems such as Advanced Mobile Phone System (AMPS) and Nordic Mobile Telephone (NMT). While older network types theoretically allocated two 25–30 kHz channels per ...
There is no GSM vs. CDMA, since 3G GSM does use CDMA. CDMA was not developed by anybody, it is just one of the different possible principles of how to manage concurrent access to one single ether. Anybody could develop his/her own TDMA, FDMA or CDMA protocol as he/her likes. -- 65.241.15.227 01:20, 10 January 2007 (UTC) [ reply ]
[1] [2] [3] In 1999 ITU approved five radio interfaces for IMT-2000 as a part of the ITU-R M.1457 Recommendation. [4] The five standards are: [5] IMT-2000 CDMA Direct Spread. also known as W-CDMA, used in UMTS, the successor to GSM; IMT-2000 CDMA Multi-Carrier. also known as CDMA2000, the successor to 2G CDMA ; IMT-2000 CDMA TDD. also known as ...