Multi-spot diversity using OFDM for 60 GHz indoor wireless LAN

To realize high data rate wireless communication systems, much attention is being paid to millimeter-wave frequencies due to large bandwidth availability and cell planning flexibility. A directive antenna at the terminal side has been considered efficient both to suppress multipath delay and to compensate large path loss. However when the direct path is blocked by obstructions such as human bodies, the performance will be degraded seriously with a directive antenna. In the 60 GHz band, this shadowing problem has been considered as a severe problem to overcome. Therefore, multi-spot diversity is suggested as anti-shadowing scheme. In multi-spot diversity, multiple base stations (BS) transmit an identical information using an identical carrier frequency and a remote terminal (RT) composes the signals from multiple BS with OFDM modulation. This system realized by OFDM can be considered as a single frequency network (SFN) applied for indoor communications. We analyze theoretically the BER performance as a function of RT position using a simple three-dimensional ray tracing model with up to two reflections in an empty hypothetical room. We show the validity of the proposed system with multiple BS compared to that with a single BS.