Mobility with mm-waves

Overcoming mm-Wave propagation and mobility challenges in 5G

Mar 19, 2018 · 2 min read

Millimeter waves

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Spectrum band occupied by millimeter waves (Credit: Qualcomm)

Available mm-Wave frequency bands

mm-Wave spectrum bands available for 5G

mm-Wave challenges

  • Wave lengths in millimeter range are obstructed by millimeter size objects. Thus, these bands work best with line of sight links. Designing a mobile network under these condition is a challenge as even the phone itself might block line of sight communication. Urban environments would experience severe path loss (refer to the following path loss map).
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28 GHz: Path loss in dense urban environment (Credit: Qualcomm)
  • Water and oxygen absorption bands result in severe attenuation in some of the frequency bands (refer to the following graph).
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Water and Oxygen absorption bands (Credit: Nutaq)

mm-Wave mobility in indoor and outdoor environments

  • mm-Wave mobility requires a rethinking of the cell boundary. In many cases, a nearby gNodeB might be blocked by an obstruction and a faraway gNodeB with direct line of sight might provide the best signal quality.
  • Attenuation through foliage would cause seasonal variations. A drive test carried out in the winter months may not be applicable after spring when the trees get back their leaves.
  • It appears walls and partitions within offices as homes may not pose a big challenge for mm-Waves. The experiments show that US style dry wall do not cause more than a couple of dB of attenuation. This may not apply to many other countries where concrete walls are used.

The following presentation from Qualcomm details the challenges and opportunities of mm-Waves.

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