Hideki Nakahara

Seamless Radio Area Formation by Distributed Antennas Using PSK-VP Scheme for Communication With High-Speed Objects

A simple distributed antenna system via simultaneous transmission using an anti-multipath modulation scheme, in which a phase variation is imposed on the symbol of a differential phase-shift keying modulation, is proposed for intended radio area formation. Based on multiray Rice channel models corresponding to linear deployment, focusing on the cell borders, fundamental error rate characteristics are revealed through simulation results, and a preferred configuration and deployment with an appropriate delay insertion plan are discussed. The proposed system achieves reliable transmission throughout a united radio area with the aid of diversity effects. Seamless transmission has been actually verified by field tests. By using downward-tilted directional base antennas, the system can extend the communication area at will while subduing outside emissions. The field tests have also shown that two-channel alternate linear deployment is realizable. Furthermore, these features remain for such fast-fading situations as not only high-speed vehicles on millimeter-wave bands but also practical baseband distribution using separate local oscillators with different carrier frequency offsets and phase noises.