Effects of Buildings – inside(Rec. P.1238)

• Path loss

  • distance and wall penetration (typically d2 to d3)
  • floor penetration (range 4-35 dB per floor)

• Multipath

  • delayed signals
    • channel impulse response
    • power delay profile
  • delay spread
    • 70 - 150 ns (~2 GHz; residential - commercial)
  • compare with symbol length

• Statistical or site-specific delay spread models

• Polarisation; building material (Rec. P.1238)

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• Site-general models indicate power loss coefficients ranging approximately from ង to ᡖ where walls and obstacles are taken into account. These values for frequencies from 900 MHz to 60 GHz. (n.b. ង for open space, ᡖ for crowded offices).

• Floor penetration depending on type of building (residential, office, commercial), and construction material (concrete floor, influence of air-conditioning units and lighting fixtures).

• Radio channel varies in time, frequency and with spatial displacement. Many propagation paths between TX and RX. Time delay associated with each path.
  • since radio channel is linear, it is fully described by its impulse response, and once impulse response is known, can determine the response of channel to any input.
  • impulse response usually described by power delay profile (power density as function of excess delay)
  • “Delay spread” is one parameter by which power delay profiles are characterised.
  • BER dependent on ratio of delay spread to symbol duration (but also ratio of wanted/unwanted amplitude depending on modulation scheme used).

• Statistical models based on representation of channel by a few multipath components; site specific models might employ ray-tracing techniques requiring detailed knowledge of indoor environment.

• Other effects dealt with in Rec. P.1238.