Optimal Packet Scheduling on an Energy Harvesting Broadcast Link

TL;DR

This paper develops an optimal offline scheduling algorithm for energy harvesting broadcast channels, minimizing transmission time by strategically deferring energy use and increasing power over time, ensuring simultaneous transmission completion.

Contribution

It introduces an adaptation of the FlowRight algorithm to solve the energy harvesting broadcast scheduling problem with proven polynomial complexity.

Findings

Algorithm converges quickly in numerical tests.

Optimal schedule defers energy use for efficiency.

Transmissions end simultaneously for all users.

Abstract

The minimization of transmission completion time for a given number of bits per user in an energy harvesting communication system, where energy harvesting instants are known in an offline manner is considered. An achievable rate region with structural properties satisfied by the 2-user AWGN Broadcast Channel capacity region is assumed. It is shown that even though all data are available at the beginning, a non-negative amount of energy from each energy harvest is deferred for later use such that the transmit power starts at its lowest value and rises as time progresses. The optimal scheduler ends the transmission to both users at the same time. Exploiting the special structure in the problem, the iterative offline algorithm, FlowRight, from earlier literature, is adapted and proved to solve this problem. The solution has polynomial complexity in the number of harvests used, and is observed to converge quickly on numerical examples.