07
Typical Penetration Loss (dB) @28GHz
Environment
Material
Thickness (cm)
Outdoor
Tinted Glass
3.8
40.1
Brick
185.4
28.3
Indoor
Clear Glass
<1.3
3.6 - 3.9
Tinted Glass
<1.3
24.5
Wall
38.1
6.8
Table 2: Typical penetration losses at 28 GHz
Frequency Band (Ghz):
28 GHz
Sparse tree (dB)
8
Dense tree (dB)
15
2 tree (dB)
19
3 tree (dB)
24
Typical foliage loss (dB)
17
Table 3: Typical foliage loss at 28 GHz
• Scattering: Objects with larger size than the propagating wavelength will cause reflection. On the other side, surface irregularity reduces the effective wavelength to create scattering. As a result, surfaces which have comparable wavelengths are common sources of scattering or diffuse reflection in mmWave propagation. The effect of scattering heavily influences mmWave channel modeling based upon ray tracing concepts. • Atmospheric Loss: Radio frequency waves while traveling through the atmosphere are absorbed by gas molecules via electric- and magnetic-dipole absorption processes, this is called atmospheric absorption losses. For the mmWave frequencies the dominant sources of atmospheric loss arise from oxygen (O2) and water vapor (H2O). The mmWave peaks are centered roughly near 23 GHz (H2O), 60 GHz (O2), 115 GHz (O2), 180 GHz (H2O) and 315 GHz (H2O). Thus, rain can create a significant impact on most popular band of mmWave deployment i: e 24-28 GHz. A typical 3 dB rain/ice margin needs to be considered while planning for 24-28 GHz bands. 2. Shorter Range- Due to the shorter wavelength of mmWave, they travel less distances in environment compared to low and mid bands. This makes the cell range shorter compared to mid and low bands. In addition to the technical challenges seen above, below mentioned are the operational challenges of mmWave due to their inherent propagation characteristics and it is very new in the cellular communications ecosystem: Addressing the Challenges of mmWave
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