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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.
In theory CDMA, TDMA and FDMA have exactly the same spectral efficiency, but, in practice, each has its own challenges – power control in the case of CDMA, timing in the case of TDMA, and frequency generation/filtering in the case of FDMA. TDMA systems must carefully synchronize the transmission times of all the users to ensure that they are ...
In dynamic time-division multiple access (dynamic TDMA), a scheduling algorithm dynamically reserves a variable number of time slots in each frame to variable bit-rate data streams, based on the traffic demand of each data stream. Dynamic TDMA is used in HIPERLAN/2 broadband radio access network. IEEE 802.16a WiMax; Bluetooth
Several ways of categorizing multiple-access schemes and protocols have been used in the literature. For example, Daniel Minoli (2009) [2] identifies five principal types of multiple-access schemes: FDMA, TDMA, CDMA, SDMA, and random access.
Both EDGE and 1xRTT are 3G standards, as defined by the ITU, but are usually marketed as 2.9G due to their comparatively low speeds and high delays when compared to true 3G technologies. True 3G systems such as EV-DO , W-CDMA (including HSPA and HSPA+ ) provide combined circuit switched and packet switched data and voice services from the ...
DAMA and PAMA are related only to channel/resource allocation and should not be confused with the multiple access/multiplexing methods (such as FDMA frequencies, TDMA slots, CDMA codes, or others) intended to divide a single communication channel into multiple virtual channels.
The access method used for IS-54 is Time Division Multiple Access (TDMA), which was the first U.S. digital standard to be developed. It was adopted by the TIA in 1992. TDMA subdivides each of the 30 kHz AMPS channels into three full-rate TDMA channels, each of which is capable of supporting a single voice call.
[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 ...