SDMA

SDMA:

SDMA by means of physical separation methods which allow the sharing of wireless channels. For example, a single channel can be used simultaneously as users far enough apart from each other to avoid interference. Known as frequency re-use, the method is widely used in cellular radio systems. Cell-sites at a distance from each other in order to minimize interference.

sdma

Juxtapose, directional antennas are used in order to avoid interference. Most of the cell sites use three antennas 120 ° sector which can make the distribution of frequencies. New technologies such as smart antennas and adaptive arrays withdraw dynamic beam forming signal to the narrow beams that can be dedicated to specific users, to the exclusion of all others.

  1. SDMA separates users on shared frequencies by isolating them with directional antennas. Most cell sites have three antenna arrays to separate their coverage to some 120 ° sector (a). Adaptive beam forming arrays used to provide the desired user while ignoring all the others on the same frequency (b).

Polarization Division Multiple Access :

A unique variant of SDMA polarization division multiple access (PDMA), separates signals by different polarizations antennas. Two different signals can then make use of the same frequency, a transmission of a vertically polarized signal and the other to the sending of a horizontally polarized signal.

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The signals do not interfere with each other. Even if they are on the same frequency as the orthogonal antennas and did not react to the contradictory polarized signal. Two orthogonal signals are stored separately with the help of horizontal and vertical receiver antennas. This technique is widely used in satellite systems.

Polarization multiplexing is also used for the optical system. The new 100-Gbit / s systems with dual-polarization quadrature phase shift (DP-QPSK) to reach a high speed in a single fiber. The high-speed data is divided into two slower flow of data, one with the help of polarization of the light vertical and the other horizontal polarization light. Polarisation filter to separate the two signals on the transmitter and receiver and to combine behind the rapid flow.

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Posted by on Jul 23 2016. Filed under Latest Updates, Mobile Communication, TECHNOLOGY, SDMA. You can follow any responses to this entry through the RSS 2.0. You can leave a response or trackback to this entry

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