  Radio frequency (RF) signals can be relied upon for conventional wireless
information transfer (WIT) and for challenging wireless power transfer (WPT),
which triggers the significant research interest in the topic of simultaneous
wireless information and power transfer (SWIPT). By further exploiting the
advanced non-orthogonal-multiple-access (NOMA) technique, we are capable of
improving the spectrum efficiency of the resource-limited SWIPT system. In our
SWIPT system, a hybrid access point (H-AP) superimposes the modulated symbols
destined to multiple WIT users by exploiting the power-domain NOMA, while WPT
users are capable of harvesting the energy carried by the superposition
symbols. In order to maximise the amount of energy transferred to the WPT
users, we propose a joint design of the energy interleaver and the
constellation rotation based modulator in the symbol-block level by
constructively superimposing the symbols destined to the WIT users in the power
domain. Furthermore, a transmit power allocation scheme is proposed to
guarantee the symbol-error-ratio (SER) of all the WIT users. By considering the
sensitivity of practical energy harvesters, the simulation results demonstrate
that our scheme is capable of substantially increasing the WPT performance
without any remarkable degradation of the WIT performance.
