GCE-BOC Modulation: A Generalized Multiplexing Technology for Modern GNSS Dual-Frequency Signals

For the purpose of structural enhancement and backwards compatibility, more than two binary signals on one carrier frequency are required to emit. In order to maximize the power efficiency, constant-envelope modulation is adopted. Alt-BOC and ACE-BOC modulations, the constant-envelope modulation that multiplexes four binary spreading codes as two QPSK signals at two different carrier frequencies, are proposed by Galileo and BeiDou respectively. A constraint of these new modulations is that the number of signals to be multiplexed must be no larger than four signal channels. In this paper, a generalized dual-frequency constant-envelope multiplexing technology, named generalized constant envelope BOC (GCE-BOC) modulation, is presented. The modulation can be regarded as the extended form of Alt-BOC and ACE-BOC modulations and provides a solution to dual-frequency constant envelope multiplexing problem for worldwide GNSS.