Delay-Optimal Resource Scheduling of Energy Harvesting based Devices

This paper investigates resource scheduling in a
wireless communication system operating with Energy Harvesting
(EH) based devices and perfect Channel State Information
(CSI). The aim is to minimize the packet loss that occurs when
the buffer is overflowed or when the queued packet is older
than a certain pre-defined threshold. We so consider a strict
delay constraint rather than an average delay constraint. The
associated optimization problem is modeled as Markov Decision
Process (MDP) where the actions are the number of packets sent
on the known channel at each slot. The optimal deterministic
offline policy is exhibited through dynamic programming techniques,
i.e. Value Iteration (VI) algorithm. We show that the
gain in the number of transmitted packets and the consumed
energy is substantial compared to: i) a naive policy which forces
the system to send the maximum number of packets using the
available energy in the battery, ii) two variants of the previous
policy that take into account the buffer state, and iii) a policy
optimized with an average delay constraint. Finally, we evaluate
our optimal policy under imperfect CSI scenario where only an
estimate of the channel state is available.