Difference between revisions of "B3-Multipath Propagation"

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== Related physics ==
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Free Space impedance <math>Z_0 </math> as connection of permeability <math>\mu_0</math> and permittivity <math>\varepsilon_0</math>.
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<math> \mu_0=4 \pi \cdot \10^{-7} N/A^2</math>. The unit of <math>\mu_0</math> is <math>Newton/Ampere^2 N/A^2 = kg m/s^2 1/A^2</math>
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<math>\varepsilon_0=\frac{1}{\mu_0 c^2} = 8.854 \cdot \10^{-12} F/m</math>. The unit of <math>\varepsilon_0</math> is Farad/m: <math>F/m = A s/V = A^2 s^4/(kg m^2)</math>

Revision as of 21:09, 20 September 2014

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⌘Multipath and how to use it

Multipath propagation Multipath propagation can be used through
  1. ) specific receivers (rake receivers)
  2. ) Multiple-input, multiple-output antenna systems (MIMO)

⌘Comments

ReceiverCharacteristics.png

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)


⌘ 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.

ReflectionScattering.png

Related physics

Free Space impedance as connection of permeability and permittivity .

. The unit of is

. The unit of is Farad/m:

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