Multi-carrier signal transmission through HVAC ducts: experimental results for channel capacity

We report, for the first time, experimental results on the channel capacity of heating, ventilation, and air-conditioning (HVAC) ducts based on a multi-carrier transmission technique and measured channel frequency responses in the 2.4 GHz industrial, scientific, and medical (ISM) band. Experiments using actual synthesized signals through a building HVAC duct system demonstrate the ability to transmit with a spectral efficiency of 3.74 bps/Hz, corresponding to over 300 Mbps transmission rate within the 2.4 GHz ISM band. The experimental results are within 80% of the theoretical maximums reported previously (see Xhafa, A.E. et al., Proc. IEEE Int. Conf. on Commun. (ICC´02), vol.2, p.936-9, 2002). For the transmission schemes employed, these results confirm the potential of using the HVAC duct channel for indoor wireless networks.