Optimal packet length using Reconfigurable Intelligent Surfaces (RIS) with thermal energy harvesting

This paper addresses the problem of maximizing both instantaneous and average throughput in wireless communication systems enhanced by Reconfigurable Intelligent Surfaces (RIS) with thermal energy harvesting. RIS technology enables programmable control over the wireless propagation environment, improving signal quality and link reliability. To ensure sustainable operation without external power sources, we propose a thermal energy harvesting framework in which energy is collected from ambient temperature gradients–an approach well-suited for environments with natural or artificial heat differentials. Within this context, we optimize the packet length to balance the trade-off between energy availability and transmission efficiency. Short packets may underutilize available energy, while overly long packets risk depleting the harvested energy budget, especially in dynamic conditions. We develop an optimization framework for selecting the packet length that maximizes both instantaneous and long-term average throughput, taking into account the harvested energy profile, temperature conditions, and RIS-assisted channel characteristics. Simulation results confirm that a well-chosen packet length significantly boosts performance and enables robust throughput, even under varying temperature gradients.