Difference between revisions of "B3-Multipath Propagation"

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==⌘Multipath and how to use it==
 
==⌘Multipath and how to use it==
 
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#) Multiple-input, multiple-output antenna systems (MIMO)
 
#) Multiple-input, multiple-output antenna systems (MIMO)
 
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=⌘ Boundary conditions =
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* What is happening on electrical walls, magnetic walls?
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[[File:DirectReflectedWave.png|450px|right|Figure: Reflection of an electromagnetic wave at the ground plane]]
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Scattering, reflection and diffraction (<span style="color:#000B80">explain differences</span>) are the three major components in wave propagation. Ideal reflection environments are characterised through <math>  |r| =1,\ \ \phi_r=180\deg </math>
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[[File:UMTScells.png|450px|right|Figure: UMTS macro and microcells in a 6-operator environment]]
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===⌘Comments===
 
===⌘Comments===

Revision as of 10:30, 21 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)


⌘ Boundary conditions

  • What is happening on electrical walls, magnetic walls?
Figure: Reflection of an electromagnetic wave at the ground plane

Scattering, reflection and diffraction (explain differences) are the three major components in wave propagation. Ideal reflection environments are characterised through

Figure: UMTS macro and microcells in a 6-operator environment


⌘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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