35 research outputs found
Achieving the Age-Energy Tradeoff with a Finite-Battery Energy Harvesting Source
We study the problem of minimizing the time-average expected Age of
Information for status updates sent by an energy-harvesting source with a
finite-capacity battery. In prior literature, optimal policies were observed to
have a threshold structure under Poisson energy arrivals, for the special case
of a unit-capacity battery. In this paper, we generalize this result to any
(integer) battery capacity, and explicitly characterize the threshold
structure. We obtain tools to derive the optimal policy for arbitrary energy
buffer (i.e. battery) size. One of these results is the unexpected equivalence
of the minimum average AoI and the optimal threshold for the highest energy
state
Age-Energy Tradeoff in Fading Channels with Packet-Based Transmissions
The optimal transmission strategy to minimize the weighted combination of age
of information (AoI) and total energy consumption is studied in this paper. It
is assumed that the status update information is obtained and transmitted at
fixed rate over a Rayleigh fading channel in a packet-based wireless
communication system. A maximum transmission round on each packet is enforced
to guarantee certain reliability of the update packets. Given fixed average
transmission power, the age-energy tradeoff can be formulated as a constrained
Markov decision process (CMDP) problem considering the sensing power
consumption as well. Employing the Lagrangian relaxation, the CMDP problem is
transformed into a Markov decision process (MDP) problem. An algorithm is
proposed to obtain the optimal power allocation policy. Through simulation
results, it is shown that both age and energy efficiency can be improved by the
proposed optimal policy compared with two benchmark schemes. Also, age can be
effectively reduced at the expense of higher energy cost, and more emphasis on
energy consumption leads to higher average age at the same energy efficiency.
Overall, the tradeoff between average age and energy efficiency is identified