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1. Study of Migration Policies in Energy-Aware Virtual Router Networks

Author

Mostafa H. Ammar, E. Miucci, and Vincenzo Eramo

Subjects
Internet, green networking, business.industry, Computer science, Distributed computing, Quality of service, ComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKS, Process (computing), Control reconfiguration, Energy consumption, virtual router migration, power saving, Markov decision process, Computer Science Applications, Modeling and Simulation, The Internet, Electrical and Electronic Engineering, Layer (object-oriented design), business, Energy (signal processing), Computer network
Abstract

The definition of a virtual router layer allows the application of energy saving techniques based on the migration of virtual routers within the physical infrastructure as traffic conditions change. As traffic decreases, physical resources can be vacated through virtual router migration, thus, saving energy. Such resources can be reclaimed if needed because of traffic increase. Unfortunately, the migration of virtual routers involves reconfiguration costs depending on implementation details and characterized, for instance, by the revenue loss due to quality-of-service (QoS) degradation during the migration process. In this paper, we propose a methodology based on the Markov decision processes for the evaluation of optimal migration policies taking into account both the operation (in terms of energy consumption) and reconfiguration costs.

Published
2014

2. Capture Effect in IEEE 802.15.4 Networks: Modelling and Experimentation

Author

Chiara Buratti, Roberto Verdone, Cengiz Gezer, C. Gezer, C. Buratti, and R. Verdone

Subjects
INTERFERENCE, business.industry, Computer science, Network packet, Decoding, ComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKS, Access control, Capture effect, Carrier-sense multiple access, COLLISION AVOIDANCE, Transceiver, business, Personal area network, IEEE 802.15, Carrier sense multiple access with collision avoidance, Computer network
Abstract

In this paper capture effect in IEEE 802.15.4 networks is studied, by means of mathematical analysis and experimentation. A Personal Area Network (PAN) composed of multiple nodes, which transmit data to a given sink by using the beacon-enabled mode of 802.15.4 Medium Access Control (MAC) protocol, is considered. Upon reception of the beacon transmitted by the PAN coordinator, the nodes transmit their packets using the slotted Carrier Sense Multiple Access with Collision Avoidance algorithm defined by the standard. A test-bed composed of 802.15.4-compliant Freescale devices is used to measure the protection ratio, that is the minimum Signal-to-Interference Ratio (SIR) which ensures the correct reception of majority of the packets. The result is, then, used to extend the developed mathematical model for beacon-enabled 802.15.4 networks. In contrast to the literature on the 802.15.4 MAC modelling, our model allows to compute the Packet Success Probability (PSP) of a node when capture effect is considered, in the scenario described. The impact of capture effect on the PSP, by varying the number of nodes, the propagation parameters and the protection ratio, is shown. The model is validated through simulations and experimental measurements. In both cases a very good agreement is found.

Published
2010