Abstract :
[en] This paper proposes an energy-efficient optimization
technique for downlink indoor visible light communication (VLC)
systems using hybrid non-orthogonal multiple access (NOMA) and
reconfigurable intelligent surfaces (RIS). The approach considers
a hybrid time division multiple access-NOMA (TDMA-NOMA) to
provide massive connectivity to multi-clusters. Clusters of users
are formed using NOMA while TDMA is used to allocate a
specific time slot within a communication frame. The proposed
technique optimizes the precoding at the multi-LED transmitter,
RIS tuning parameters, and time-slot allocation parameters for
each cluster to maximize the system’s energy efficiency (EE). The
EE optimization problem is solved through the block coordinate
descent (BCD) framework, which splits the optimization problem
into two blocks. An alternating optimization (AO) framework is
used in the first block to optimize the transmit precoding through
conic quadratic programming (CQP) and RIS tuning parameters
through a semidefinite programming (SDP) technique based on the
surrogate optimization method. The second block allocates energyefficient time-slot for each cluster through linear programming
(LP) approach to further improve the EE of the system. The
simulation results indicate that the proposed BCD framework
achieves fast convergence and excellent performance in terms of the
EE of the system while maintaining low computational complexity.
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