Enhanced Fluid Index Modulation for Integrated Data and Energy Transfer
For wireless networks requiring both data and energy transfer, this work provides a novel method to improve the rate-energy trade-off, though it is incremental as it applies existing FAS and FIM concepts to IDET.
This paper proposes a fluid index modulation (FIM) assisted integrated data and energy transfer (IDET) system, deriving closed-form expressions for average harvested power, BER, and achievable data rate, and developing an alternating optimization framework that achieves near-optimal performance with significantly lower complexity than exhaustive search.
Integrated data and energy transfer (IDET) is a promising technique for supporting sustainable low-power wireless networks. To improve both communication reliability and energy transfer efficiency, this paper investigates a fluid index modulation (FIM) assisted IDET system, where the base station employs a two-dimensional fluid antenna system (FAS) and the receiver adopts a power-splitting architecture. In FIM, the information bits are delivered not only from the modulation symbols, but also the index of antenna position. Under finite-alphabet signaling, the average harvested power, bit error rate (BER), and achievable data rate are derived in closed form. A joint optimization problem is formulated to maximize the average harvested power subject to BER and achievable rate constraints by jointly optimizing the port selection, precoding vector, and power splitting ratio. An alternating optimization framework is developed, where the precoding vector and port selection are obtained via a Riemannian augmented Lagrangian method (RALM) and block coordinate descent (BCD) algorithm, respectively. Simulation results demonstrate that the proposed scheme achieves a superior rate-energy trade-off over benchmark schemes, while the proposed algorithm attains near-optimal performance with significantly lower complexity than exhaustive search.