3,691 research outputs found
Energy-Efficient Flow Scheduling and Routing with Hard Deadlines in Data Center Networks
The power consumption of enormous network devices in data centers has emerged
as a big concern to data center operators. Despite many
traffic-engineering-based solutions, very little attention has been paid on
performance-guaranteed energy saving schemes. In this paper, we propose a novel
energy-saving model for data center networks by scheduling and routing
"deadline-constrained flows" where the transmission of every flow has to be
accomplished before a rigorous deadline, being the most critical requirement in
production data center networks. Based on speed scaling and power-down energy
saving strategies for network devices, we aim to explore the most energy
efficient way of scheduling and routing flows on the network, as well as
determining the transmission speed for every flow. We consider two general
versions of the problem. For the version of only flow scheduling where routes
of flows are pre-given, we show that it can be solved polynomially and we
develop an optimal combinatorial algorithm for it. For the version of joint
flow scheduling and routing, we prove that it is strongly NP-hard and cannot
have a Fully Polynomial-Time Approximation Scheme (FPTAS) unless P=NP. Based on
a relaxation and randomized rounding technique, we provide an efficient
approximation algorithm which can guarantee a provable performance ratio with
respect to a polynomial of the total number of flows.Comment: 11 pages, accepted by ICDCS'1
Real-Time and Energy-Efficient Routing for Industrial Wireless Sensor-Actuator Networks
With the emergence of industrial standards such as WirelessHART, process industries are adopting Wireless Sensor-Actuator Networks (WSANs) that enable sensors and actuators to communicate through low-power wireless mesh networks. Industrial monitoring and control applications require real-time communication among sensors, controllers and actuators within end-to-end deadlines. Deadline misses may lead to production inefficiency, equipment destruction to irreparable financial and environmental impacts. Moreover, due to the large geographic area and harsh conditions of many industrial plants, it is labor-intensive or dan- gerous to change batteries of field devices. It is therefore important to achieve long network lifetime with battery-powered devices.
This dissertation tackles these challenges and make a series of contributions. (1) We present a new end-to-end delay analysis for feedback control loops whose transmissions are scheduled based on the Earliest Deadline First policy. (2) We propose a new real-time routing algorithm that increases the real-time capacity of WSANs by exploiting the insights of the delay analysis. (3) We develop an energy-efficient routing algorithm to improve the network lifetime while maintaining path diversity for reliable communication. (4) Finally, we design a distributed game-theoretic algorithm to allocate sensing applications with near-optimal quality of sensing
Energy efficient scheduling for cluster-tree wireless sensor networks with time-bounded data flows: application to IEEE 802.15.4/ZigBee
Cluster scheduling and collision avoidance are crucial issues in large-scale cluster-tree Wireless Sensor Networks
(WSNs). The paper presents a methodology that provides a Time Division Cluster Scheduling (TDCS) mechanism
based on the cyclic extension of RCPS/TC (Resource Constrained Project Scheduling with Temporal Constraints)
problem for a cluster-tree WSN, assuming bounded communication errors. The objective is to meet all end-to-end
deadlines of a predefined set of time-bounded data flows while minimizing the energy consumption of the nodes by
setting the TDCS period as long as possible. Sinceeach cluster is active only once during the period, the end-to-end
delay of a given flow may span over several periods when there are the flows with opposite direction. The scheduling
tool enables system designers to efficiently configure all required parameters of the IEEE 802.15.4/ZigBee beaconenabled
cluster-tree WSNs in the network design time. The performance evaluation of thescheduling tool shows that the
problems with dozens of nodes can be solved while using optimal solvers
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