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Path correlation

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Joseph Shapira
Joseph Shapira

The correlation of multi-propagation paths is an indicator for the effectiveness of diversity reception, transmission and MIMO. The penetration of the waves into buildings is limited to distinct passages through windows, and decorrelation is introduced through multiple reflections inside. This is analysed.

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Path Correlation through Penetration to Buildings Dr. Joseph Shapira 1
Contents 1. 2. 3. 4. 5. 6. 1. 2. Propagation modes Sources of waves impinging on the outer wall Reflection and transmission through walls Transmission through apertures Propagation within a room Coupling into inner rooms Indoors-generated transmission Paths correlation Correlation between impinging sources Correlation between offspring branches diffractions of each penetration mode) (reflections and 2
Propagation modes 1. 2. 3. 4. 5. 6. Impinging waves Wall penetration Aperture penetration 1 Transmission through multiple walls Propagation within the room Coupling to inner rooms 5 4 3 6 2 3
Sources of waves impinging on the outer wall 1. 2. 3. 4. Direct (LOS) 1. Remote source plane wave. Full correlation between source antennas. 2. Near source (across the street). Full de-correlation at edges of the aperture dD 了R d source antennas spacing; D aperture; R- distance Remote reflector each reflector is a remote source. The distance between the reflectors d, determines the correlation between them. Over the roof, and around-the-wall diffraction these are line sources. Create a single ray in the plane of the line. Propagation along the street (waveguide propagation). Impinges on the wall at low grazing angle, high attenuation. Reflectors or line diffractors across the street, generate wave impinging near normal incidence and may be stronger. 4
Transmission through the wall the angular filter T T H polarization V polarization (incidence in horizonthal plane) 5
Window penetration First Fresnel zone s2 d= 4了 Diffraction zone attenuated by ceiling and furniture clutter W Wi = exp{ 留d } Transition zone W = 錚 A 錚 錚 錚 Wi 錚 了d 錚 2 錚 了 錚 錚 錚 2h 錚 錚 h 2 了d h> 4s holds for W,Wi flux density, i incident 1st Fresnel zone Edge diffraction 6
The window penetration depth cos 2 Free space penetration depth filter d ' = ( s 2 4了 ) cos 2 d d ' 7
Wall reflection loss Reflection loss [dB] -5.00 88 80 72 64 56 48 40 32 8 24 -3.00 16 Reflection loss [dB] 0 -1.00 V polarization TE, eps=3 TM, eps=6 -7.00 -9.00 TM, Eps=3 H polarization -11.00 TE, eps=6 TM, eps=10 TE, eps=10 -13.00 -15.00 Angle from zenit, degrees 8
Room reflections The reflection loss is not trivial Up to 10 dB per reflection. The direct ray is dominant 慮 180慮 6 Scattering from objects near the UE (e.g person) competes with high order reflection 180+慮 4 慮 2 9
Reference to reported observations Mischa Dohler et. Al. :MiMO channel measurements, IEEE Communications Magazine March 2007 Most contributions are LOS. Then only single bounce counts. Others, and diffractions, are too small Propagation along corridor key-hole effect. DOA is only along the corridor axis. Clustered multipath are correlated 10
Direction-of-arrival measurements A. Molisch. The BS was placed across the street against the building 11
Indoor-generated transmission Reciprocity imples dominance of direct + 1st reflection Within the same room scattering rich. Through walls to other rooms angular filter through each wall. However, multiple rays may have equal strength (due to complexity of environment, e.g. corridor propagation etc.). A range of richness dimensions. Indoors to outdoors by reciprocity, same as out-indoors. 12
Correlation analysis LOS remote source penetrates the wall/ window as a plane wave. Full correlation. Edge diffraction of the window is directive. The diffraction of both edges overlap too far to meet the de-correlation condition 了R dD Over-the-roof diffraction is coherent in the horizontal plane. Around-the-corner diffraction is coherent in the vertical plane. The outer wall/ window does not change the correlation of the penetrating waves. However, it acts as an angular filter, limiting the range of incidence. Indoor reflections are attenuated. Only direct and 1 st bounce count. The correlation of the incoming waves does not change. 13
Correlation analysis - 2 The indoor multipath is mainly of order 1 2 (diffraction by a close-by object may add). The degree of source depends on the number of angularly separated reflection/ scattering that hit the wall with similar strength through the wall angular filter. This may typically be 1 2. The MIMO degree is then Most then then rarely 11 12 22 higher 14
Dr Joseph Shapira Comm&Sens Ltd jshapira@netvision.net.il www.comm-and-sens.com 15

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Path correlation

  • 1. Path Correlation through Penetration to Buildings Dr. Joseph Shapira 1
  • 2. Contents 1. 2. 3. 4. 5. 6. 1. 2. Propagation modes Sources of waves impinging on the outer wall Reflection and transmission through walls Transmission through apertures Propagation within a room Coupling into inner rooms Indoors-generated transmission Paths correlation Correlation between impinging sources Correlation between offspring branches diffractions of each penetration mode) (reflections and 2
  • 3. Propagation modes 1. 2. 3. 4. 5. 6. Impinging waves Wall penetration Aperture penetration 1 Transmission through multiple walls Propagation within the room Coupling to inner rooms 5 4 3 6 2 3
  • 4. Sources of waves impinging on the outer wall 1. 2. 3. 4. Direct (LOS) 1. Remote source plane wave. Full correlation between source antennas. 2. Near source (across the street). Full de-correlation at edges of the aperture dD 了R d source antennas spacing; D aperture; R- distance Remote reflector each reflector is a remote source. The distance between the reflectors d, determines the correlation between them. Over the roof, and around-the-wall diffraction these are line sources. Create a single ray in the plane of the line. Propagation along the street (waveguide propagation). Impinges on the wall at low grazing angle, high attenuation. Reflectors or line diffractors across the street, generate wave impinging near normal incidence and may be stronger. 4
  • 5. Transmission through the wall the angular filter T T H polarization V polarization (incidence in horizonthal plane) 5
  • 6. Window penetration First Fresnel zone s2 d= 4了 Diffraction zone attenuated by ceiling and furniture clutter W Wi = exp{ 留d } Transition zone W = 錚 A 錚 錚 錚 Wi 錚 了d 錚 2 錚 了 錚 錚 錚 2h 錚 錚 h 2 了d h> 4s holds for W,Wi flux density, i incident 1st Fresnel zone Edge diffraction 6
  • 7. The window penetration depth cos 2 Free space penetration depth filter d ' = ( s 2 4了 ) cos 2 d d ' 7
  • 8. Wall reflection loss Reflection loss [dB] -5.00 88 80 72 64 56 48 40 32 8 24 -3.00 16 Reflection loss [dB] 0 -1.00 V polarization TE, eps=3 TM, eps=6 -7.00 -9.00 TM, Eps=3 H polarization -11.00 TE, eps=6 TM, eps=10 TE, eps=10 -13.00 -15.00 Angle from zenit, degrees 8
  • 9. Room reflections The reflection loss is not trivial Up to 10 dB per reflection. The direct ray is dominant 慮 180慮 6 Scattering from objects near the UE (e.g person) competes with high order reflection 180+慮 4 慮 2 9
  • 10. Reference to reported observations Mischa Dohler et. Al. :MiMO channel measurements, IEEE Communications Magazine March 2007 Most contributions are LOS. Then only single bounce counts. Others, and diffractions, are too small Propagation along corridor key-hole effect. DOA is only along the corridor axis. Clustered multipath are correlated 10
  • 11. Direction-of-arrival measurements A. Molisch. The BS was placed across the street against the building 11
  • 12. Indoor-generated transmission Reciprocity imples dominance of direct + 1st reflection Within the same room scattering rich. Through walls to other rooms angular filter through each wall. However, multiple rays may have equal strength (due to complexity of environment, e.g. corridor propagation etc.). A range of richness dimensions. Indoors to outdoors by reciprocity, same as out-indoors. 12
  • 13. Correlation analysis LOS remote source penetrates the wall/ window as a plane wave. Full correlation. Edge diffraction of the window is directive. The diffraction of both edges overlap too far to meet the de-correlation condition 了R dD Over-the-roof diffraction is coherent in the horizontal plane. Around-the-corner diffraction is coherent in the vertical plane. The outer wall/ window does not change the correlation of the penetrating waves. However, it acts as an angular filter, limiting the range of incidence. Indoor reflections are attenuated. Only direct and 1 st bounce count. The correlation of the incoming waves does not change. 13
  • 14. Correlation analysis - 2 The indoor multipath is mainly of order 1 2 (diffraction by a close-by object may add). The degree of source depends on the number of angularly separated reflection/ scattering that hit the wall with similar strength through the wall angular filter. This may typically be 1 2. The MIMO degree is then Most then then rarely 11 12 22 higher 14
  • 15. Dr Joseph Shapira Comm&Sens Ltd jshapira@netvision.net.il www.comm-and-sens.com 15
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