283 research outputs found
On the Stability of Random Multiple Access with Stochastic Energy Harvesting
In this paper, we consider the random access of nodes having energy
harvesting capability and a battery to store the harvested energy. Each node
attempts to transmit the head-of-line packet in the queue if its battery is
nonempty. The packet and energy arrivals into the queue and the battery are all
modeled as a discrete-time stochastic process. The main contribution of this
paper is the exact characterization of the stability region of the packet
queues given the energy harvesting rates when a pair of nodes are randomly
accessing a common channel having multipacket reception (MPR) capability. The
channel with MPR capability is a generalized form of the wireless channel
modeling which allows probabilistic receptions of the simultaneously
transmitted packets. The results obtained in this paper are fairly general as
the cases with unlimited energy for transmissions both with the collision
channel and the channel with MPR capability can be derived from ours as special
cases. Furthermore, we study the impact of the finiteness of the batteries on
the achievable stability region.Comment: The material in this paper was presented in part at the IEEE
International Symposium on Information Theory, Saint Petersburg, Russia, Aug.
201
Interference-Based Optimal Power-Efficient Access Scheme for Cognitive Radio Networks
In this paper, we propose a new optimization-based access strategy of
multipacket reception (MPR) channel for multiple secondary users (SUs)
accessing the primary user (PU) spectrum opportunistically. We devise an
analytical model that realizes the multipacket access strategy of SUs that
maximizes the throughput of individual backlogged SUs subject to queue
stability of the PU. All the network receiving nodes have MPR capability. We
aim at maximizing the throughput of the individual SUs such that the PU's queue
is maintained stable. Moreover, we are interested in providing an
energy-efficient cognitive scheme. Therefore, we include energy constraints on
the PU and SU average transmitted energy to the optimization problem. Each SU
accesses the medium with certain probability that depends on the PU's activity,
i.e., active or inactive. The numerical results show the advantage in terms of
SU throughput of the proposed scheme over the conventional access scheme, where
the SUs access the channel randomly with fixed power when the PU is sensed to
be idle
Effect of Energy Harvesting on Stable Throughput in Cooperative Relay Systems
In this paper, the impact of energy constraints on a two-hop network with a
source, a relay and a destination under random medium access is studied. A
collision channel with erasures is considered, and the source and the relay
nodes have energy harvesting capabilities and an unlimited battery to store the
harvested energy. Additionally, the source and the relay node have external
traffic arrivals and the relay forwards a fraction of the source node's traffic
to the destination; the cooperation is performed at the network level. An inner
and an outer bound of the stability region for a given transmission probability
vector are obtained. Then, the closure of the inner and the outer bound is
obtained separately and they turn out to be identical. This work is not only a
step in connecting information theory and networking, by studying the maximum
stable throughput region metric but also it taps the relatively unexplored and
important domain of energy harvesting and assesses the effect of that on this
important measure.Comment: 20 pages, 4 figure
Q-learning Channel Access Methods for Wireless Powered Internet of Things Networks
The Internet of Things (IoT) is becoming critical in our daily life. A key technology of interest in this thesis is Radio Frequency (RF) charging. The ability to charge devices wirelessly creates so called RF-energy harvesting IoT networks. In particular, there is a hybrid access point (HAP) that provides energy in an on-demand manner to RF-energy harvesting devices. These devices then collect data and transmit it to the HAP. In this respect, a key issue is ensuring devices have a high number of successful transmissions.
There are a number of issues to consider when scheduling the transmissions of devices in the said network. First, the channel gain to/from devices varies over time. This means the efficiency to deliver energy to devices and to transmit the same amount of data is different over time. Second, during channel access, devices are not aware of the energy level of other devices nor whether they will transmit data. Third, devices have non-causal knowledge of their energy arrivals and channel gain information. Consequently, they do not know whether they should delay their transmissions in hope of better channel conditions or less contention in future time slots or doing so would result in energy overflow
Combining distributed queuing with energy harvesting to enable perpetual distributed data collection applications
This is the peer reviewed version of the following article: Vazquez-Gallego F, Tuset-Peiró P, Alonso L, Alonso-Zarate J. Combining distributed queuing with energy harvesting to enable perpetual distributed data collection applications. Trans Emerging Tel Tech. 2017;e3195 , which has been published in final form at https://doi.org/10.1002/ett.3195. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.This paper presents, models, and evaluates energy harvesting–aware distributed queuing (EH-DQ), a novel medium access control protocol that combines distributed queuing with energy harvesting (EH) to address data collection applications in industrial scenarios using long-range and low-power wireless communication technologies. We model the medium access control protocol operation using a Markov chain and evaluate its ability to successfully transmit data without depleting the energy stored at the end devices. In particular, we compare the performance and energy consumption of EH-DQ with that of time-division multiple access (TDMA), which provides an upper limit in data delivery, and EH-aware reservation dynamic frame slotted ALOHA, which is an improved variation of frame slotted ALOHA. To evaluate the performance of these protocols, we use 2 performance metrics: delivery ratio and time efficiency. Delivery ratio measures the ability to successfully transmit data without depleting the energy reserves, whereas time efficiency measures the amount of data that can be transmitted in a certain amount of time. Results show that EH-DQ and TDMA perform close to the optimum in data delivery and outperform EH-aware reservation dynamic frame slotted ALOHA in data delivery and time efficiency. Compared to TDMA, the time efficiency of EH-DQ is insensitive to the amount of harvested energy, making it more suitable for energy-constrained applications. Moreover, compared to TDMA, EH-DQ does not require updated network information to maintain a collision-free schedule, making it suitable for very dynamic networks.Peer ReviewedPostprint (author's final draft
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