Characterization of Indoor Heating, Ventilation and Air Conditioning Duct System as a Communication Channel at 60 GHz

In this paper, we demonstrate heating, ventilation, and air conditioning (HVAC) ducts as viable and inexpensive high-speed communications links inside of buildings at millimeter wave (mm-wave) frequencies. We show the impulse response characteristics and calculate the power delay profile for the HVAC duct. In order to show the viability of HVAC duct system with transmitter effective isotropic radiated power (EIRP) as 7 dBm, we calculate the received signal strength indicator (RSSI) which varies between -30 dBm to -50 dBm for the ducts of various shapes and lengths (up to 8 m) at 60 GHz. We also calculate the dispersion encountered and the root-mean-square (RMS) delay spread. The RMS delay spread is shown to be 9 ns for a 5 m duct length. It is also shown that reliable indoor communication with data rates in excess of 800 Mbps over a distance up to 10 m is possible using HVAC ducts with transmitter EIRP of 7 dBm at 60 GHz.