Abstract
In this paper, we propose a fluid antenna (FA)
enabled joint transmit and receive index modulation (FA-JTRIM) transmission mechanism for reconfigurable intelligent surface (RIS)-assisted millimeter-wave (mmWave) communication
systems. By integrating the methodologies of FA and IM, the
proposed scheme achieves enhanced spectral efficiency (SE) while
requiring only a single radio frequency (RF) chain at both the
transmitter and receiver. The proposed scheme offers a low hardware cost and power consumption transmission mechanism for
the RIS-aided mmWave communication systems. Specifically, the
encoding of information bits encompasses not only the modulated
symbol but also the indices of transmit FA positions and receive
antennas. To achieve a reliability-complexity trade-off, two types
of detectors are introduced for the proposed FA-JTR-IM scheme,
including the optimal maximum likelihood (ML) detector and
two-step sequential (TSS) detector. Based on the ML detector,
we derive the expression for the conditional pair-wise error
probability of the proposed FA-JTR-IM scheme. Additionally,
we provide the closed-form expressions for the unconditional
PEP under the finite-path and infinite-path channel conditions,
respectively. Simulation results demonstrate the superiority of
the proposed FA-JTR-IM scheme in terms of error performance
over its conventional benchmark schemes under the same SE
condition