Link Energy Consumption Research Articles

Energy and institution size.

Why do institutions grow? Despite nearly a century of scientific effort, there remains little consensus on this topic. This paper offers a new approach that focuses on energy consumption. A systematic relation exists between institution size and energy consumption per capita: as energy consumption increases, institutions become larger. I hypothesize that this relation results from the interplay between technological scale and human biological limitations. I also show how a simple stochastic model can be used to link energy consumption with firm dynamics.

Efficient algorithm for energy-aware virtual network embedding

Network virtualization is a promising approach for resource management that allows customized Virtual Networks (VNs) to be multiplexed on a shared physical infrastructure. A key function that network virtualization can provide is Virtual Network Embedding (VNE), which maps virtual networks requested by users to a shared substrate network maintained by an Internet service provider. Existing research has worked on this, but has primarily focused on maximizing the revenue of the Internet service provider. In this paper, we consider energy-aware virtual network embedding, which aims at minimizing the energy consumption for embedding virtual networks in a substrate network. In our optimization model, we consider energy consumption of both links and nodes. We propose an efficient heuristic to assign virtual nodes to appropriate substrate nodes based on priority, where existing activated nodes have higher priority for hosting newly arrived virtual nodes. In addition, our proposed algorithm can take advantage of activated links for embedding virtual links so as to minimize total energy consumption. The simulation results show that, for all the cases considered, our algorithm can improve upon previous work by an average of 12.6% on acceptance rate, while the consumed energy can be reduced by 12.34% on average.

Coding Schemes to Minimize Energy Consumption of Communication Links in Wireless Nanosensor Networks

It is critical to design energy-efficient communication technologies for wireless nanosensor networks (WNSNs) as nanosensors are highly energy-constrained. This paper focuses on WNSNs adopting the on – off keying (OOK) modulator. So far, some existing low-weight (LW) codes with low average codeword weight (ACW) map source symbols into different codewords with fewer high bits so as to greatly reduce the transmission energy at the transmitter. However, the transmission energy reduction is achieved at the price of large reception energy at the receiver as the codeword lengths of LW codes are large, incurring their ineffectiveness in most scenarios. To remedy the problem, we design the fixed-length minimum-communication-energy (F-MCE) code and variable-length minimum-communication-energy (V-MCE) code to minimize the total energy consumption at the transmitter and receiver for point-to-point communication in OOK-based WNSNs. Specifically, the code design problems are formulated as integer nonlinear programming (INLP) problems, and the F-MCE and V-MCE codes are obtained by solving the INLP problems. The F-MCE and V-MCE codes are applicable in more scenarios than the LW code. Extensive experimental results show that the V-MCE always outperforms the LW code regarding the energy saving, while the F-MCE code achieves energy saving no less than that of the existing LW codes.

Low-Power Hybrid Memory Cubes With Link Power Management and Two-Level Prefetching

The hybrid memory cube (HMC) is a 3-D-stacked DRAM architecture designed for substantially improved memory bandwidth. In particular, its I/O interface achieves up to 320 GB/s of external bandwidth through high-speed serial links. However, it comes at the cost of large static power of off-chip links, which dominates total power consumption of HMCs. In this paper, we propose an adaptive mechanism to partially disable off-chip links of HMCs to reduce the energy consumption of the off-chip links. In order to determine the number of the links to be disabled upon application loads, we develop a simple hardware module called link delay monitor to simulate all different link configurations at the same time and find the largest number of the links to be disabled while satisfying the given performance constraint. We also present two-level prefetching with in-HMC prefetch buffers to further improve the efficiency of our link power management scheme in the presence of prefetching. Evaluations show that our scheme reduces the energy consumption of HMCs by 52% on average with a negligible performance degradation.

Energy and Institution Size

Why do institutions grow? Despite nearly a century of scientific effort, there remains little consensus on this topic. This paper offers a new approach that focuses on energy consumption. A systematic relation exists between institution size and energy consumption per capita: as energy consumption increases, institutions become larger. I hypothesize that this relation results from the interplay between technological complexity and human biological limitations. I also show how a simple stochastic model can be used to link energy consumption with firm dynamics.

Efficient energy conservation in MANET using Energy Conserving Advanced Optimised Link State Routing model

ABSTRACTMobile Ad-hoc Network (MANET) is formed dynamically by the independent organisation of the mobile nodes connected through wireless links without using any centralised administration. Energy consumption is the most significant issue in the MANETs, since most of the mobile hosts operate on limited battery resources. Reduction in the energy consumption results in the increase in the lifetime and throughput of the network. The performance of existing techniques was less in terms of energy conservation issues. To overcome these limitations, this paper proposes an energy conservation mechanism integrated with a proactive MANET routing scheme. The routing schema is based on the energy level and the mobility of the nodes. Calculation of energy cost is performed based on the prediction of the energy consumption level of the node, using Energy Conserving Advanced Optimised Link State Routing (ECAO) model. The performance of the proposed ECAO model is compared with the existing Optimised Link State Routing and Advanced Optimised Link State Routing models. From the comparison result, it is clearly observed that the proposed model achieves better performance in terms of number of TC messages, Packet Delivery Ratio, average time, end-to-end delay, and link delay and energy consumption.

Energy-aware node and link reconfiguration for virtualized network environments

Energy consumption in information and communications technology (ICT) accounts for a large portion of the total energy consumed in industrial countries, which is rapidly increasing. Virtualized network environments (VNEs) have recently emerged as a solution in this technology to address the challenges of future Internet. VNEs also play a fundamental role toward virtualizing data centers. Consequently, it is essential to develop novel techniques for reducing the energy consumption of VNEs. In this paper, we discuss multiple energy-saving solutions that locally optimize the node and link energy consumption of VNEs during the off-peak period by reconfiguring the mapping of already allocated virtual nodes and links. The proposed reconfigurations enable the providers to adjust the level of the reconfiguration and accordingly control possible traffic disruptions. An integer linear program (ILP) is formulated for each solution. Because the defined ILPs are NP-hard, a novel heuristic algorithm is also proposed. The proposed energy-saving methods are evaluated over random VNE scenarios. The results confirm that the solutions save notable amounts of energy in physical nodes and links during the off-peak period.

Energy Efficiency of VCSELs in the Context of Short-Range Optical Links

We present results from an investigation of the energy efficiency of vertical cavity surface emitting lasers (VCSELs) under large signal modulation. We show that the most important factor influencing the energy consumption of the VCSELs is the required optical modulation amplitude, which drives other VCSEL design requirements. The required optical modulation amplitude also depends on the optical link design. Through this dependence, it is possible to better understand the energy consumption of complete short-range optical links.

Strategies and Services for Energy Efficiency in Real-Time Ethernet Networks

The IEEE 802.3az amendment to the Ethernet standard, referred to as energy-efficient Ethernet (EEE), encompasses the new low power Idle operational mode that allows to strongly decrease the energy consumption of inactive links. The introduction of EEE in real-time industrial communications represents an interesting topic currently addressed by the scientific community, as well as by some standardization bodies. The outcomes of these activities are promising, since effective EEE strategies can be devised, and are able to cope with the very tight timing requirements of industrial communication. Unfortunately, the proposed analyses do not address implementation issues that, conversely, represent a crucial aspect in this scenario. Hence, in this paper, we specifically focus on practical issues concerned with the adoption of EEE strategies by real-time Ethernet (RTE) networks. At first, we address the use of commercially available network components and describe a measurement setup that can be adopted to achieve the adequate characterization of such components. Furthermore, we show that, in an RTE perspective, link activations/deactivations should be independently managed by suitably designed EEE strategies at the application level. Consequently, we defined a set of network services that have to be made available in the device drivers. Hence, we consider a generic RTE network and discuss methods for the practical implementation of those EEE strategies. A performance assessment carried out via theoretical models as well as numerical simulations shows that EEE strategies can be effectively implemented with considerable power savings at the expense of only minimal performance degradation.

Energy-efficient Routing in MIMO-based Mobile Ad hoc Networks with Multiplexing and Diversity Gains

It is critical to design energy-efficient routing protocols for battery-limited mobile ad hoc networks, especially in which the energy-consuming MIMO techniques are employed. However, there are several challenges in such a design: first, it is difficult to characterize the energy consumption of a MIMO-based link; second, without a careful design, the broadcasted RREP packets, which are used in most energy-efficient routing protocols, could flood over the networks, and the destination node cannot decide when to reply the communication request; third, due to node mobility and persistent channel degradation, the selected route paths would break down frequently and hence the protocol overhead is increased further. To address these issues, in this paper, a novel Greedy Energy-Efficient Routing (GEER) protocol is proposed: (a) a generalized energy consumption model for the MIMO-based link, considering the trade-off between multiplexing and diversity gains, is derived to minimize link energy consumption and obtain the optimal transmit model; (b) a simple greedy route discovery algorithm and a novel adaptive reply strategy are adopted to speed up path setup with a reduced establishment overhead; (c) a lightweight route maintenance mechanism is introduced to adaptively rebuild the broken links. Extensive simulation results show that, in comparison with the conventional solutions, the proposed GEER protocol can significantly reduce the energy consumption by up to 68.74%.

Monitoring and optimization of energy consumption of base transceiver stations

The growth and development of the mobile phone network has led to an increased demand for energy by the telecommunications sector, with a noticeable impact on the environment.Monitoring of energy consumption is a great tool for understanding how to better manage this consumption and find the best strategy to adopt in order to maximize reduction of unnecessary usage of electricity. This paper reports on a monitoring campaign performed on six BSs (Base Transceiver Stations) located central Italy, with different technology, typology and technical characteristics.The study focuses on monitoring energy consumption and environmental parameters (temperature, noise, and global radiation), linking energy consumption with the load of telephone traffic and with the air conditioning functions used to cool the transmission equipment. Moreover, using experimental data collected, it is shown, with a Monte Carlo simulation based on power saving features, how the BS monitored could save energy.

Bicriteria Optimization in Wireless Sensor Networks: Link Scheduling and Energy Consumption

Link scheduling is important for reliable data communication in wireless sensor networks. Previous works mainly focus on how to find the minimum scheduling length but ignore the impact of energy consumption. In this paper, we integrate them together and solve them by multiobjective genetic algorithms. As a contribution, by jointly modeling the route selection and interference-free link scheduling problem, we give a systematical analysis on the relationship between link scheduling and energy consumption. Considering the specific many-to-one communication nature of WSNs, we propose a novel link scheduling scheme based on NSGA-II (Non-dominated Sorting Genetic Algorithm II). Our approach aims to search the optimal routing tree which satisfies the minimum scheduling length and energy consumption for wireless sensor networks. To achieve this goal, the solution representation based on the routing tree, the genetic operations including tree based recombination and mutation, and the fitness evaluation based on heuristic link scheduling algorithm are well designed. Extensive simulations demonstrate that our algorithm can quickly converge to the Pareto optimal solution between the two performance metrics.

Applications of Decision Making with Uncertain Information

In the process of decision making, a variety of unpredictable factors can result in imprecise information, which can be classified into randomness, fuzziness and uncertainty within mathematical frameworks. Accordingly, probability theory, fuzzy set theory and uncertainty theory, respectively, have been used to describe and handle these types of uncertainties. Moreover, as multi-fold uncertainties can often occur simultaneously in a complicated system, fuzzy random theory and uncertain random theory have been also developed to handle mixed models of uncertainty. Typically, all these approaches can provide efficient methodologies to handle real-world uncertain information. This special issue aims to cover all aspects of employing uncertain technologies to find optimal solutions and assist in making the best possible decisions. It also intends to provide the readership with the recent and significant research on the theoretical results in the framework of uncertain technologies and their applications to a variety of real-world problems, including transportation, management, information systems, economics, supply chain, finance, among others. After the call for papers was announced in late January, 2013, this special issue has been attracted tremendous attentions from a lot of researchers. Totally, we had received 15 manuscripts before the submission deadline. After a rigorous review process, only five papers are finally accepted for publication in this special issue. The first paper by Lixing Yang et al. proposed an integer programming model for train scheduling on a single-track railway line by using space-time network representation. In their research, the velocity choice is considered to decrease the expected energy consumption and interactions between different trains, where link energy consumption is deduced by Davis formula. The second paper by Meiyi Wei et al. proposed a chance-constrained programming model for the hazardous materials transportation within the framework of credibility theory, which aims to obtain the tradeoff between the transportation risk and cost. The third paper by Yuhan Liu et al. formulated an uncertain currency model by considering the foreign exchange rate as an uncertain processes described by uncertain differential equations driven by Liu process. Furthermore, European and American currency option pricing formulas were derived for the proposed uncertain currency model. The fourth paper by Jinwu Gao and Kai Yao proposed an uncertain random process as a generalization of both stochastic process and uncertain process, and some special types of uncertain random processes such as stationary increment process and renewal process were also discussed. The fifth paper by Hua Ke et al. considered a project scheduling problem in the environment with uncertainty and randomness, and a hybrid intelligent algorithm was proposed to search the quasi-optimal schedules. Finally, we in particular thank Editor-in-Chief and all the reviewers for their kind supports in the process of organization and review for this special issue.

A Coordinated Routing Model with Optimized Velocity for Train Scheduling on a Single-Track Railway Line

Train scheduling aims to seek a set of space-time paths for multiple trains on a railway line such that resources can be utilized efficiently with respect to prespecified criteria. By representing the train trajectory through a time-space path in its space-time network, this paper proposes an integer programming model for train scheduling on a single-track railway line, in which velocity choice is particularly considered to further decrease the expected energy consumption and interactions between different trains, and the link energy consumption is derived by the Davis formula with respect to different train speeds. The proposed model is implemented in the GAMS optimization software to solve an approximate optimal solution. Numerical examples show that the optimal timetable with optimized velocities can further decrease the energy consumption and coupling effects in comparison to the fixed velocity based schedule.

Enhanced Low Complex Double Error Correction Coding with Crosstalk Avoidance for Reliable On-Chip Interconnection Link

As the technology scales down, shrinking geometry and layout dimension, on- chip interconnects are exposed to different noise sources such as crosstalk coupling, supply voltage fluctuation and temperature variation that cause random and burst errors. These errors affect the reliability of the on-chip interconnects. Hence, error correction codes integrated with noise reduction techniques are incorporated to make the on-chip interconnects robust against errors. The proposed error correction code uses triplication error correction scheme as crosstalk avoidance code (CAC) and a parity bit is added to it to enhance the error correction capability. The proposed error correction code corrects all the error patterns of one bit error, two bit errors. The proposed code also corrects 7 out of 10 possible three bit error patterns and detects burst errors of three. Hybrid Automatic Repeat Request (HARQ) system is employed when burst errors of three occurs. The performance of the proposed codec is evaluated for residual flit error rate, codec area, power, delay, average flit latency and link energy consumption. The proposed codec achieves four magnitude order of low residual flit error rate and link energy minimization of over 53 % compared to other existing error correction schemes. Besides the low residual flit error rate, and link energy minimization, the proposed codec also achieves up to 4.2 % less area and up to 6 % less codec power consumption compared to other error correction codes. The less codec area, codec power consumption, low link energy and low residual flit error rate make the proposed code appropriate for on chip interconnection link.

A Energy Saving Routing Algorithm Based on Shortest Path Tree

The optimal energy saving routing algorithm proposed in this paper is based on the shortest path tree. This algorithm introduces the concept of node classification and builds the weight function based on link energy consumption factor, neighbor node’s residual energy factor and type weight and so on. It uses different weight factor according to different types of nodes, and finally generates the shortest path tree, all nodes send data to sink node along the shortest path tree. The simulation results show that the algorithm can prolong the network life time, balance energy consumption of each node, and reduce the average network delay.

Improved Energy Efficiency for Optical Transport Networks by Elastic Forward Error Correction

In this paper we propose a scheme for reducing the energy consumption of optical links by means of adaptive forward error correction (FEC). The scheme works by performing on the fly adjustments to the code rate of the FEC, adding extra parity bits to the data stream whenever extra capacity is available. We show that this additional parity information decreases the number of necessary decoding iterations and thus reduces the power consumption in iterative decoders during periods of low load. The code rate adjustments can be done on a frame-by-frame basis and thus make it possible to manipulate the balance between effective data rate and FEC coding gain without any disruption to the live traffic. As a consequence, these automatic adjustments can be performed very often based on the current traffic demand and bit error rate performance of the links through the network. The FEC scheme itself is designed to work as a transparent add-on to transceivers running the optical transport network (OTN) protocol, adding an extra layer of elastic soft-decision FEC to the built-in hard-decision FEC implemented in OTN, while retaining interoperability with existing OTN equipment. In order to facilitate dynamic code rate adaptation, we propose a programmable encoder and decoder design approach, which can implement various codes depending on the desired code rate using the same basic circuitry. This design ensures optimal coding gain performance with a modest overhead for supporting multiple codes with minimal impact on the area and power requirements of the decoder.

Qos Constraints-Based Energy-Efficient Model for IP Networks

This paper proposes an energy-efficient model to overcome the energy-efficient problem in large-scale IP networks, based on QoS constraints. To characterize network energy consumption, we present a link energy consumption model based on the sleep and speed scaling mechanisms. If there is no traffic on a link, let it sleep, or activate it and divide its energy consumption into base energy consumption and traffic energy consumption. And then according to the link energy consumption model, we can build our energy-efficient model to improve the network energy efficiency. Finally, simulation results show that our model can significantly improve the network energy efficiency.

Delay Analysis of Timer-Based Frame Coalescing in Energy Efficient Ethernet

IEEE 802.3az, also known as Energy Efficient Ethernet (EEE), aims at reducing the energy consumption of an Ethernet link by placing it in sleep mode when the link is idle. Frame coalescing mechanism proposed for EEE is an effective means to increase the average idle time of the link, thus reducing the overhead stemming from sleep/wake transitions, but at the expense of increased frame delays. Therefore, it is imperative to quantify the energy-delay trade-off while employing frame coalescing. As opposed to existing delay models that focus only on the average delays, a simple but exact queuing model is introduced for timer-based frame coalescing to find the delay distribution when the frame arrival process is Poisson and frame lengths are generally distributed. An expression for average saving in power consumption is also provided.

Application-Specific Network-on-Chip synthesis with flexible router Placement

Network-on-Chip (NoC) has been proposed as a possible solution to the communication problem in nanoscale System-on-Chip (SoC) design. NoC architectures with optimized application-specific topologies have been found to be superior to the regular architectures in designing Multi-Processor System-on-Chip (MPSoC) solutions. The application specific NoC design problem takes as input the chip floorplan, library of NoC components, and communication requirements between the tasks of the application. It outputs the positions of the routers in the floorplan, such that, all communication requirements of the application are satisfied. This paper presents an Integer Linear Programming formulation of the problem, followed by a heuristic technique based on Particle Swarm Optimization (PSO) for finding the router positions from the set of available positions within the chip floorplan. The goal is to minimize the communication cost between cores, satisfying both the link length and router port constraints. The results have been shown on realistic benchmarks. Comparisons have been carried out with regular mesh and custom architectures having routers positioned at (i) the corners of the cores, (ii) the centers of the cores, and (iii) the intersections of the cores. Significant reductions in communication cost have been observed over all the cases. For smaller benchmarks, the optimum results obtained via ILP matches exactly with those reported by the PSO. Many of the existing router placement policies fail even for these small benchmarks, when restrictions are imposed on permissible link length. This establishes the merit of the PSO formulation. Link and router energy consumption of the synthesized NoC have been compared with regular mesh based architectures. The results show significant reduction in communication cost, area overhead, link energy and router energy in the synthesized NoC over regular mesh topology as well.