Difference between revisions of "B3-Multipath Propagation"
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− | ==⌘Multipath and how to use it | + | =⌘ B3-Multipath Propagation = |
+ | {{Building Networks TOC}} | ||
+ | =⌘Multipath and how to use it= | ||
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|[[File:5-10.jpg|400px|Multipath propagation]] | |[[File:5-10.jpg|400px|Multipath propagation]] | ||
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#) Multiple-input, multiple-output antenna systems (MIMO) | #) Multiple-input, multiple-output antenna systems (MIMO) | ||
|} | |} | ||
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+ | ''Note:'' The mobile phone users will typically not have a direct link between the mobile phone and the antennas of the base station in a typical environment. Such a situation, where the mobile communication has to go "around a building" or "around the corner" are called '''NLOS''', non Line-of-Sight connection. As compared to a Line-of-Sight '''LOS''' connection the signal is typically reduced by some 20-30 dB. | ||
+ | |||
+ | =⌘ Boundary conditions = | ||
+ | * What is happening on electrical walls, magnetic walls? | ||
+ | |||
+ | [[File:DirectReflectedWave.png|450px|right|Figure: Reflection of an electromagnetic wave at the ground plane]] | ||
+ | |||
+ | 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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===⌘Comments=== | ===⌘Comments=== | ||
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* 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) | * 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. | ||
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+ | When the surface becomes extremely rough, and with roughness ''>> lambda'', then the reflected wave will be scattered into any direction. | ||
+ | |[[File:ReflectionScattering.png|450px]] | ||
+ | |} | ||
+ | |||
+ | == Related physics == | ||
+ | Free Space impedance <math>Z_0 </math> as connection of permeability <math>\mu_0</math> and permittivity <math>\varepsilon_0</math>. | ||
+ | |||
+ | <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} </math> <br/> | ||
+ | <math> = 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> | ||
+ | |||
+ | = Diffraction = | ||
+ | Diffraction is the transforming of a wave at an object, typical edge of a house ("edge diffraction") or the roof-top | ||
+ | |||
+ | = Scattering = | ||
+ | Interaction with object being about the same size as the wavelength, <math> lambda... </math> |
Latest revision as of 10:34, 17 October 2016
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Contents
⌘ B3-Multipath Propagation
⌘Multipath and how to use it
Multipath propagation can be used through
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Note: The mobile phone users will typically not have a direct link between the mobile phone and the antennas of the base station in a typical environment. Such a situation, where the mobile communication has to go "around a building" or "around the corner" are called NLOS, non Line-of-Sight connection. As compared to a Line-of-Sight LOS connection the signal is typically reduced by some 20-30 dB.
⌘ 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
⌘Comments
⌘ Reflection
Related physics
Free Space impedance as connection of permeability and permittivity .
. The unit of is
.
The unit of is Farad/m:
Diffraction
Diffraction is the transforming of a wave at an object, typical edge of a house ("edge diffraction") or the roof-top
Scattering
Interaction with object being about the same size as the wavelength,