141 research outputs found
Energy-Efficient Transmission Schedule for Delay-Limited Bursty Data Arrivals under Non-Ideal Circuit Power Consumption
This paper develops a novel approach to obtaining energy-efficient
transmission schedules for delay-limited bursty data arrivals under non-ideal
circuit power consumption. Assuming a-prior knowledge of packet arrivals,
deadlines and channel realizations, we show that the problem can be formulated
as a convex program. For both time-invariant and time-varying fading channels,
it is revealed that the optimal transmission between any two consecutive
channel or data state changing instants, termed epoch, can only take one of the
three strategies: (i) no transmission, (ii) transmission with an
energy-efficiency (EE) maximizing rate over part of the epoch, or (iii)
transmission with a rate greater than the EE-maximizing rate over the whole
epoch. Based on this specific structure, efficient algorithms are then
developed to find the optimal policies that minimize the total energy
consumption with a low computational complexity. The proposed approach can
provide the optimal benchmarks for practical schemes designed for transmissions
of delay-limited data arrivals, and can be employed to develop efficient online
scheduling schemes which require only causal knowledge of data arrivals and
deadline requirements.Comment: 30 pages, 7 figure
Optimal Quality-of-Service Scheduling for Energy-Harvesting Powered Wireless Communications
XiaojingChen, Wei Ni, Xin Wang, YichuangSun, “Optimal Quality-of-Service Scheduling for Energy-Harvesting Powered Wireless Communications”, IEEE Transactions on Wireless Communications, Vol. 15 (5): 3269-3280, January 2016. © 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.In this paper, a new dynamic string tautening algorithm is proposed to generate the most energy-efficient off-line schedule for delay-limited traffic of transmitters with non-negligible circuit power. The algorithm is based on two key findings that we derive through judicious convex formulation and resultant optimality conditions, specifies a set of simple but optimal rules, and generates the optimal schedule with a low complexity of O(N2) in the worst case. The proposed algorithm is also extended to on-line scenarios, where the transmit schedule is generated on-the-fly. Simulation shows that the proposed algorithm requires substantially lower average complexity by almost two orders of magnitude to retain optimality than general convex solvers. The effective transmit region, specified by the tradeoff of the data arrival rate and the energy harvesting rate, is substantially larger using our algorithm than using other existing alternatives. Significantly more data or less energy can be supported in the proposed algorithm.Peer reviewedFinal Accepted Versio
Energy Harvesting Broadband Communication Systems with Processing Energy Cost
Communication over a broadband fading channel powered by an energy harvesting
transmitter is studied. Assuming non-causal knowledge of energy/data arrivals
and channel gains, optimal transmission schemes are identified by taking into
account the energy cost of the processing circuitry as well as the transmission
energy. A constant processing cost for each active sub-channel is assumed.
Three different system objectives are considered: i) throughput maximization,
in which the total amount of transmitted data by a deadline is maximized for a
backlogged transmitter with a finite capacity battery; ii) energy maximization,
in which the remaining energy in an infinite capacity battery by a deadline is
maximized such that all the arriving data packets are delivered; iii)
transmission completion time minimization, in which the delivery time of all
the arriving data packets is minimized assuming infinite size battery. For each
objective, a convex optimization problem is formulated, the properties of the
optimal transmission policies are identified, and an algorithm which computes
an optimal transmission policy is proposed. Finally, based on the insights
gained from the offline optimizations, low-complexity online algorithms
performing close to the optimal dynamic programming solution for the throughput
and energy maximization problems are developed under the assumption that the
energy/data arrivals and channel states are known causally at the transmitter.Comment: published in IEEE Transactions on Wireless Communication
Energy Harvesting Wireless Communications: A Review of Recent Advances
This article summarizes recent contributions in the broad area of energy
harvesting wireless communications. In particular, we provide the current state
of the art for wireless networks composed of energy harvesting nodes, starting
from the information-theoretic performance limits to transmission scheduling
policies and resource allocation, medium access and networking issues. The
emerging related area of energy transfer for self-sustaining energy harvesting
wireless networks is considered in detail covering both energy cooperation
aspects and simultaneous energy and information transfer. Various potential
models with energy harvesting nodes at different network scales are reviewed as
well as models for energy consumption at the nodes.Comment: To appear in the IEEE Journal of Selected Areas in Communications
(Special Issue: Wireless Communications Powered by Energy Harvesting and
Wireless Energy Transfer
Wireless Power Transfer and Data Collection in Wireless Sensor Networks
In a rechargeable wireless sensor network, the data packets are generated by
sensor nodes at a specific data rate, and transmitted to a base station.
Moreover, the base station transfers power to the nodes by using Wireless Power
Transfer (WPT) to extend their battery life. However, inadequately scheduling
WPT and data collection causes some of the nodes to drain their battery and
have their data buffer overflow, while the other nodes waste their harvested
energy, which is more than they need to transmit their packets. In this paper,
we investigate a novel optimal scheduling strategy, called EHMDP, aiming to
minimize data packet loss from a network of sensor nodes in terms of the nodes'
energy consumption and data queue state information. The scheduling problem is
first formulated by a centralized MDP model, assuming that the complete states
of each node are well known by the base station. This presents the upper bound
of the data that can be collected in a rechargeable wireless sensor network.
Next, we relax the assumption of the availability of full state information so
that the data transmission and WPT can be semi-decentralized. The simulation
results show that, in terms of network throughput and packet loss rate, the
proposed algorithm significantly improves the network performance.Comment: 30 pages, 8 figures, accepted to IEEE Transactions on Vehicular
Technolog
Datacenter Traffic Control: Understanding Techniques and Trade-offs
Datacenters provide cost-effective and flexible access to scalable compute
and storage resources necessary for today's cloud computing needs. A typical
datacenter is made up of thousands of servers connected with a large network
and usually managed by one operator. To provide quality access to the variety
of applications and services hosted on datacenters and maximize performance, it
deems necessary to use datacenter networks effectively and efficiently.
Datacenter traffic is often a mix of several classes with different priorities
and requirements. This includes user-generated interactive traffic, traffic
with deadlines, and long-running traffic. To this end, custom transport
protocols and traffic management techniques have been developed to improve
datacenter network performance.
In this tutorial paper, we review the general architecture of datacenter
networks, various topologies proposed for them, their traffic properties,
general traffic control challenges in datacenters and general traffic control
objectives. The purpose of this paper is to bring out the important
characteristics of traffic control in datacenters and not to survey all
existing solutions (as it is virtually impossible due to massive body of
existing research). We hope to provide readers with a wide range of options and
factors while considering a variety of traffic control mechanisms. We discuss
various characteristics of datacenter traffic control including management
schemes, transmission control, traffic shaping, prioritization, load balancing,
multipathing, and traffic scheduling. Next, we point to several open challenges
as well as new and interesting networking paradigms. At the end of this paper,
we briefly review inter-datacenter networks that connect geographically
dispersed datacenters which have been receiving increasing attention recently
and pose interesting and novel research problems.Comment: Accepted for Publication in IEEE Communications Surveys and Tutorial
- …