Evaluation of Synchronized SS-CDMA for QZSS Safety Confirmation System

Suguru Kameda, Akinori Taira, Yuji Miyake, Noriharu Suematsu, Tadashi Takagi, Kazuo Tsubouchi

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)


In this paper, we investigate the realization of synchronized spread spectrum code division multiple access (synchronized SS-CDMA) for the quasi-zenith satellite system (QZSS) safety confirmation system during major disasters. The QZSS is expected to provide a highly accurate positioning service and allow two-way communication, which includes the terminal location and short messages. The proposed synchronized SS-CDMA scheme realizes direct access from mobile terminals to the satellite and the simultaneous transmission of many users using SS codes with a large spreading factor. All terminals synchronize their own clock and frequency with those of the global navigation satellite system (GNSS). In this scheme, maintaining orthogonality among users in both the time and frequency domains is the most important problem. In this paper, for the consideration of mobile use, the effect of residual timing jitter and frequency offset in a fading environment is evaluated by computer simulation. As a result, acceptable timing and frequency errors for terminals are clarified in order for the system to be viable using the GNSS.

Original languageEnglish
Article number8667690
Pages (from-to)4846-4856
Number of pages11
JournalIEEE Transactions on Vehicular Technology
Issue number5
Publication statusPublished - 2019 May


  • frequency offset
  • global navigation satellite system (GNSS)
  • positioning signal
  • Satellite communication
  • short-message communication
  • synchronization
  • timing jitter


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