Search results
Results from the WOW.Com Content Network
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.
TDMA frame structure showing a data stream divided into frames and those frames divided into time slots. Time-division multiple access (TDMA) is a channel access method for shared-medium networks. It allows several users to share the same frequency channel by dividing the signal into different time slots. [1]
An advanced form is dynamic TDMA (DTDMA), where an assignment of transmitters to time slots varies on each frame. Multi-frequency time-division multiple access (MF-TDMA) combines time and frequency multiple access. As an example, 2G cellular systems are based on a combination of TDMA and FDMA
For a classic example for understanding the fundamental difference of TDMA and CDMA, imagine a cocktail party where couples are talking to each other in a single room. The room represents the available bandwidth: TDMA: A speaker takes turns talking to a listener. The speaker talks for a short time and then stops to let another couple talk.
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.
A spreading code is a pseudo-random code in the time domain that has a narrow ambiguity function in the frequency domain, unlike other narrow pulse codes. In CDMA a locally generated code runs at a much higher rate than the data to be transmitted. Data for transmission is combined by bitwise XOR (exclusive OR) with the faster code. The figure ...
Single-carrier FDMA (SC-FDMA) is a frequency-division multiple access scheme. Originally known as Carrier Interferometry , it is also called linearly precoded OFDMA ( LP-OFDMA ). Like other multiple access schemes (TDMA, FDMA, CDMA, OFDMA), it deals with the assignment of multiple users to a shared communication resource.
Time-division multiple access (TDMA) divides a channel into frames, which furthermore are subdivided into a vast number of time slots. Users transmit in rapid succession, one after the other, each using their own time slot. One of the drawbacks of TDMA is that it requires a central station for slot assignment and time synchronization.