3 research outputs found
Active Status Update Packet Drop Control in an Energy Harvesting Node
This paper considers an energy harvesting sensor node with battery size
that recharges its battery through an incremental energy harvesting
process and receives updates from a single information source in slotted time.
The node actively decides to power down (OFF) or up (ON) the communication
circuitry for a portion of its operation time in order to maintain energy
efficiency. Update packets arriving in ON (OFF) periods are received
(discarded). A deterministic energy cost per time is paid during ON periods.
The power down decision can be in partial or full nature, yielding various
options for deciding ON-OFF intervals. We develop age-threshold based power
ON-OFF schemes to minimize age of information at the node subject to energy
harvesting constraints with partial and full power down options for
and cases
Resource Allocation in Green Dense Cellular Networks: Complexity and Algorithms
This paper studies the problem of user association, scheduling and channel
allocation in dense cellular networks with energy harvesting base stations
(EBSs). In this problem, the EBSs are powered solely by renewable energy and
each user has a request for downloading data of certain size with a deadline
constraint. The objective is to maximize the number of associated and scheduled
users while allocating the available channels to the users and respecting the
energy and deadline constraints. First, the computational complexity of this
problem is characterized by studying its NP-hardness in different cases. Next,
efficient algorithms are proposed in each case. The case of a single channel
and a single EBS is solved using two polynomial-time optimal algorithms---one
for arbitrary deadlines and a less-complex one for common deadlines. The case
of a single channel and multiple EBSs is solved by proposing an efficient
constant-factor approximation algorithm. The case of multiple channels is
efficiently solved using a heuristic algorithm. Finally, our theoretical
analysis is supplemented by simulation results to illustrate the performance of
the proposed algorithms.Comment: Submitted to TV
Energy-Efficient Buffer-Aided Relaying Systems with Opportunistic Spectrum Access
In this paper, an energy-efficient cross-layer design framework is proposed
for cooperative relaying networks, which takes into account the influence of
spectrum utilization probability. Specifically, random arrival traffic is
considered and an adaptive modulation and coding (AMC) scheme is adopted in the
cooperative transmission system to improve the system performance. The average
packet dropping rate of the relay-buffer is studied at first. With the packet
dropping rate and stationary distribution of the system state, the closed-form
expression of the delay is derived. Then the energy efficiency for
relay-assisted transmission is investigated, which takes into account the
queueing process of the relay and the source. In this context, an energy
efficiency optimization problem is formulated to determine the optimum strategy
of power and time allocation for the relay-assisted cooperative system.
Finally, the energy efficient switching strategy between the relay assisted
transmission and the direct transmission is obtained, where packet
transmissions have different delay requirements. In addition, energy efficient
transmission policy with AMC is obtained. Numerical results demonstrate the
effectiveness of the proposed design improving the energy efficiency