A technique for wireless LAN connection through building concrete wall at 2.4GHz

A technique for wireless LAN connection through building concrete wall is proposed. The propagation loss in a 10 cm-thick concrete is found at about -8.9 dB at 2.4 GHz by simulation and experiment. Using a large aperture horn antenna mounted flush on the back of wall, the attenuated signal power is raked over a wide area and reradiated into a space behind the wall via a small second antenna connected back-to-back to the first one in the downlink. It is possible to make the reradiated field in a limited region near the second antenna nearly as strong as that of the wave incident on the wall. An unlicensed small-power relay station based on the IEEE802.11 g/b standards is placed in this region to complete the downlink. In the uplink, the signal power from the relay station antenna is picked up by the second antenna and radiated into the space outside the wall. An amplifier of about 13 dB gain is required in the uplink in order to make the uplink versus downlink link budgets balanced. The amplifier gain is so set as to comply with the limit set by regulatory agency. The proposed method is analyzed by 3D simulation and its feasibility is supported by experiment.