Hitoshi Takai

In-room transmission BER performance of anti-multipath modulation PSK-VP

The BER (bit error rate) performance of an anti-multipath modulation pi /4-QPSK-VP is evaluated in comparison to a conventional differential pi /4-QPSK, when applied to high-speed digital radio transmission within a room where both transmitting and receiving antennas are set up, using a transmission experiment and a BER calculation. Through this transmission experiment at about 3 and 6 Mb/s, pi /4-QPSK-VP was confirmed to improve the BER significantly for both data rates in two test rooms. A delay profile measurement was additionally carried out to characterize the propagation channels of the test rooms and to find out an appropriate channel model. The BER calculation based on the above channel model, which was confirmed to estimate the upper bound of a floor error rate sufficiently in comparison to the transmission experiment, reveals the relationship between the data rate and the BER and indicates an optimum and a maximum data rate for pi /4-QPSK-VP with respect to the maximum delay spread of the room. The results show that pi /4-QPSK-VP is estimated to raise the available data rate up to about 20 times over that of pi /4-QPSK for a BER of 10/sup -4/, although pi /4-APSK-VP requires twice the transmission bandwidth. >

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.