SISO Versus MIMO RF Antennas

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SISO [Single Input Single Output] systems, or single frequency - single antennas are subject to space, time, and frequency fading.

MIMO [Multiple Input Multiple Output] or multiple antennas and/or multiple frequencies which increases coverage, increase data rates, and reduces c0-channel interference.

Linear Polarization is the direction of the E [Electric] field of the EM [ElectroMagnetic] wave in the form of:

• Vertical - perpendicular to the earth (ground)

• Horizontal - parallel to the earth (ground)
• Oblique
• Cross (signals on the same frequency but polarized differently)

HSDPA also uses a wide variety of RF [Radio Frequency] techniques to provide this service. Here are a few of the many potential concepts being explored.

Spatial Diversity is provided by transmitting identical information via channels via uncorrelated fading (separating the channels via 10-20 radio frequency wavelengths or in polarization orientation - horizontal or vertical). SDMA [Space Division Multiple Access] or SDM [Space Division Multiplexing] can be used to increase the downlink cell throughput by scheduling packets to users served by different beams.

This limits mutual interference between these users making it possible to reuse the same channelization code resources. Beamforming is used to increase throughput by user-specific beamforming and beamforming with a grid of fixed beams (using a dedicated scrambling code which can be assigned to each beam making a channelization code tree in each beam).

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[tags]hsdpa,mimo,beamforming,siso,spatial diversity[/tags]