Experimental evaluation of transmission timing control method for QZSS short message synchronized SS-CDMA communication

We have proposed synchronized spread-spectrum code-division multiple-access (SS-CDMA) communication for location and short message communication system using Quasi-Zenith Satellite System (QZSS) as a safety confirmation system at the time of great disaster. In this communication, the satellite reception timings of all uplink signals are synchronized using transmission timing control method in order to realize high-density user multiple access. However, an error may occur in the satellite reception timing due to the terminal time deviation and the calculation error of propagation delay to the satellite. In this paper, we measure the terminal time deviation and the propagation delay calculation error at the same time and evaluate the satellite reception timing error of the uplink signal. By this measurement, it is shown that satellite reception timing error within 50 ns can be realized in 99.98% of mobile terminals (MTs). This shows that high-density use multiple access can be realized by transmission timing control method using satellite positioning signals.