Overlapped-spot diversity using orthogonal frequency division multiplexing for 60 GHz indoor wireless local area network

This paper proposes an anti-shadowing scheme employing site diversity combined with orthogonal frequency division multiplexing (OFDM) modulation for 60 GHz wireless LAN. In the proposed system which we name overlapped-spot diversity, multiple access points (APs) sufficiently separated on a ceiling cover a same terminal so that it can receive more than one direct LOS paths even under shadowing situation. By using OFDM modulation, multiple APs within a single cell can transmit identical information using an identical frequency band while a terminal can simply add up all the arrived signals from those APs without any specific combining technique. Our computer simulation results by means of ray-tracing showed the system with multiple APs achieves better robustness to shadowing compared to that with single AP in terms of average bit error rate and outage probability