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A related concept is the combination of a single carrier transmission with the single-carrier frequency-domain-equalization (SC-FDE) scheme. [10] The single carrier transmission, unlike SC-FDMA and OFDM, employs no IDFT or DFT at the transmitter, but introduces the cyclic prefix to transform the linear channel convolution into a circular one.
Frequency-division multiple access (FDMA) is a channel access method used in some multiple-access protocols. FDMA allows multiple users to send data through a single communication channel, such as a coaxial cable or microwave beam, by dividing the bandwidth of the channel into separate non-overlapping frequency sub-channels and allocating each sub-channel to a separate user.
The code-division multiple access (CDMA) scheme is based on spread spectrum, meaning that a wider radio channel bandwidth is used than the data rate of individual bit streams requires, and several message signals are transferred simultaneously over the same carrier frequency, utilizing different spreading codes.
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.
In the context of 3G systems, the integration of Time-Division Multiple Access (TDMA) with Code-Division Multiple Access (CDMA) and Time-Division Duplexing (TDD) in the Universal Mobile Telecommunications System (UMTS) represents a sophisticated approach to optimizing spectrum efficiency and network performance.
Single-Carrier Frequency Domain Equalization (SC-FDE) is a single-carrier (SC) modulation combined with frequency-domain equalization (FDE). It is an alternative approach to inter symbol interference (ISI) mitigation.
Carrier-sense multiple access with collision avoidance (CSMA/CA) in computer networking, is a network multiple access method in which carrier sensing is used, but nodes attempt to avoid collisions by beginning transmission only after the channel is sensed to be "idle". [1] [2] When they do transmit, nodes transmit their packet data in its entirety.
Given a carrier frequency offset,Δ, the received continuous-time signal will be rotated by a constant frequency and is in the form of , = | = (+) + + The carrier frequency offset can first be normalized with respect to the sub carrier spacing (= / ()) and then decomposed into the integral component () and fractional component (), that is, = (+) and <.