6,976 research outputs found
Implementing energy saving algorithms for Ethernet link aggregates with ONOS
During the last few years, there has been plenty of research for reducing
energy consumption in telecommunication infrastructure. However, many of the
proposals remain unim-plemented due to the lack of flexibility in legacy
networks. In this paper we demonstrate how the software defined networking
(SDN) capabilities of current networking equipment can be used to implement
some of these energy saving algorithms. In particular, we developed an ONOS
application to realize an energy-aware traffic scheduler to a bundle link made
up of Energy Efficient Ethernet (EEE) links between two SDN switches. We show
how our application is able to dynamically adapt to the traffic characteristics
and save energy by concentrating the traffic on as few ports as possible. This
way, unused ports remain in Low Power Idle (LPI) state most of the time, saving
energy.Comment: 8 pages, 10 figure
Collaborative Storage Management In Sensor Networks
In this paper, we consider a class of sensor networks where the data is not
required in real-time by an observer; for example, a sensor network monitoring
a scientific phenomenon for later play back and analysis. In such networks, the
data must be stored in the network. Thus, in addition to battery power, storage
is a primary resource: the useful lifetime of the network is constrained by its
ability to store the generated data samples. We explore the use of
collaborative storage technique to efficiently manage data in storage
constrained sensor networks. The proposed collaborative storage technique takes
advantage of spatial correlation among the data collected by nearby sensors to
significantly reduce the size of the data near the data sources. We show that
the proposed approach provides significant savings in the size of the stored
data vs. local buffering, allowing the network to run for a longer time without
running out of storage space and reducing the amount of data that will
eventually be relayed to the observer. In addition, collaborative storage
performs load balancing of the available storage space if data generation rates
are not uniform across sensors (as would be the case in an event driven sensor
network), or if the available storage varies across the network.Comment: 13 pages, 7 figure
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Optimizing the beacon exchange rate for proactive autonomic configuration in ubiquitous MANETs
Proactive self-configuration is indispensable for MANETs like ubiquitous sensor networks (USNs), as component devices of the network are usually exposed to natural or man-made disasters due to the hostile deployment and ad hoc nature of the USNs. Network state beacons (NSBs) are exchanged among the key nodes of the network for crucial and effective monitoring of the network for steady state operation. The rate of beacon exchange (F/sub E/) and its contents, define the time and nature of the proactive action. Therefore it is very important to optimize these parameters to tune the functional response of the USN. This paper presents a comprehensive model for monitoring and proactively reconfiguring the network by optimizing the F/sub E/. The results confirm the improved throughput while maintaining QoS over longer periods of network operation
An Energy-Efficient, Dynamic Voltage Scaling Neural Stimulator for a Proprioceptive Prosthesis
Accepted versio
Performance Modelling and Optimisation of Multi-hop Networks
A major challenge in the design of large-scale networks is to predict and optimise the
total time and energy consumption required to deliver a packet from a source node to a
destination node. Examples of such complex networks include wireless ad hoc and sensor
networks which need to deal with the effects of node mobility, routing inaccuracies, higher
packet loss rates, limited or time-varying effective bandwidth, energy constraints, and the
computational limitations of the nodes. They also include more reliable communication
environments, such as wired networks, that are susceptible to random failures, security
threats and malicious behaviours which compromise their quality of service (QoS) guarantees.
In such networks, packets traverse a number of hops that cannot be determined
in advance and encounter non-homogeneous network conditions that have been largely
ignored in the literature. This thesis examines analytical properties of packet travel in
large networks and investigates the implications of some packet coding techniques on both
QoS and resource utilisation.
Specifically, we use a mixed jump and diffusion model to represent packet traversal
through large networks. The model accounts for network non-homogeneity regarding
routing and the loss rate that a packet experiences as it passes successive segments of a
source to destination route. A mixed analytical-numerical method is developed to compute
the average packet travel time and the energy it consumes. The model is able to capture
the effects of increased loss rate in areas remote from the source and destination, variable
rate of advancement towards destination over the route, as well as of defending against
malicious packets within a certain distance from the destination. We then consider sending
multiple coded packets that follow independent paths to the destination node so as to
mitigate the effects of losses and routing inaccuracies. We study a homogeneous medium
and obtain the time-dependent properties of the packet’s travel process, allowing us to
compare the merits and limitations of coding, both in terms of delivery times and energy
efficiency. Finally, we propose models that can assist in the analysis and optimisation
of the performance of inter-flow network coding (NC). We analyse two queueing models
for a router that carries out NC, in addition to its standard packet routing function. The
approach is extended to the study of multiple hops, which leads to an optimisation problem
that characterises the optimal time that packets should be held back in a router, waiting
for coding opportunities to arise, so that the total packet end-to-end delay is minimised
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