⌘Multipath and how to use it
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Multipath propagation can be used through
- ) specific receivers (rake receivers)
- ) Multiple-input, multiple-output antenna systems (MIMO)
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⌘ Boundary conditions
- What is happening on electrical walls, magnetic walls?
Scattering, reflection and diffraction (explain differences) are the three major components in wave propagation. Ideal reflection environments are characterised through
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Receiver characteristics for usage of reflections in impulse response
- sliding 16 mu s window and integration of power in this window (typical GSM)
- Rake receiver, where each finger of the receiver points to one reflection (typical enhanced GSM, UMTS)
- MIMO (Multiple input, multiple output) or smart antenna arrays. Here we use spatial filtering, assuming that radiation comes in from different directions (typical 802.11n, smart antennas for UMTS)
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⌘ Reflection
Reflection at a perfectly plane gives a reflection coefficient r= -1. When the surface gets rougher, reflection is still in the main direction, but the reflected power is spread around the main reflection angle. Assuming that no absorption takes place, then the total reflected power is constant.
When the surface becomes extremely rough, and with roughness >> lambda, then the reflected wave will be scattered into any direction.
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Related physics
Free Space impedance as connection of permeability and permittivity .
. The unit of is
. The unit of is Farad/m: