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We present a novel protocol for IEEE 802.15.4 beacon-less sensor networks, which provides support to RSSI-based localization algorithms to estimate the position of mobile nodes. The proposed protocol is designed to allow the application to change the mobile node operation mode on demand. In this way it is possible to manage the trade-off between energy consumption and achieved position accuracy. First...
In this paper, deployment strategies of underwater sensor nodes and gateway nodes for two-dimensional communication architecture in Underwater Acoustic Wireless Sensor Networks (UWSNs) are proposed. In the sensor deployment strategy, underwater sensor nodes are deployed in two rows along the coastline, which is of complete coverage and connectivity, localization available and scalable. In the gateway...
We propose the asynchronous receiver-initiated MAC protocol with the stair-like sleep that each node reduces its own sleep time by the sleep-change-rate depending on the number of hops from the source to the sink in wireless sensor networks (WSNs). Using the stair-like sleep, our protocol achieves the high delivery ratio, the low packet delay, and the high energy efficiency due to the reduction of...
In this paper, we generalize the problem of network coded cooperative data exchange from a fixed broadcast topology to dynamic networks with mobile peers. In this problem a group of wireless clients are interested in obtaining a set of packets through cooperation, where each client initially holds a subset of packets. Unlike recent studies where cooperation is enabled through a fixed error free broadcast...
In this paper, the tapered-VTH methodology to design energy-efficient buffers in deep nanometer CMOS technology is deeply analyzed. Its effectiveness is demonstrated under various working conditions (variable final load, activity factor, supply voltage and process corner). Simulations based on a 45-nm technology showed that the tapered-VTH approach can provide a 3X energy reduction, at the parity...
This paper introduces four path-based DVFS algorithms for embedded multimedia applications. Application model consists of multiprocessor scheduled task-graphs and input class probability distributions. Design constraints are a soft delay deadline and a minimum completion ratio. The algorithms target four scenarios that correspond to systems with various DVFS and quality of service monitoring capabilities...
Advances in technology of semiconductor make nowadays possible to design Chip Multiprocessor Systems equipped with huge on-chip Last Level Caches. Due to the wire delay problem, the use of traditional cache memories with a uniform access time would result in unacceptable response latencies. NUCA (Non Uniform Cache Access) architecture has been proposed as a viable solution to hide the adverse impact...
Given a 16-bit or 32-bit overclocked ripple-carry adder, we minimize error by allocating multiple supply voltages to the gates. We solve the error minimization problem for a fixed energy budget using a binned geometric program solution (BGPS). A solution found via BGPS outperforms the two best prior approaches, uniform voltage scaling and biased voltage scaling, reducing error by as much as a factor...
Voltage and frequency scaling (VFS) for NoC can potentially reduce energy consumption, but the associated increase in latency and degradation in throughput limits its deployment. We propose flexible-pipeline routers that reconfigure pipeline stages upon VFS, so that latency through such routers remains constant. With minimal hardware overhead, the deployment of such routers allows us to reduce network...
The current networks are often designed with redundancy in order to deal with unexpected failures, but this makes a large amount of energy consumption and bandwidth waste. In the real networks, the performance is limited by the link's capacity which gives an upper bound of the traffic amount conveying through the links. In order to explore energy saving methods in the networks, we consider a model...
Energy consumption is a major issue in data centers operating 24 hours a day, 7 days a week. The power dissipated by a web cluster is not proportional to the numbers of incoming requests if only DVFS (Dynamic Voltage Frequency Scaling) is used. This is because of the nonlinear power efficiency of DVFS, the large load fluctuation in web services and the typical CPU utilization rates of a server. This...
This paper studies gradient routing with two-hop information for industrial wireless sensor network to enhance real-time performance with energy efficiency. The two-hop information routing is adopted as that in two-hop velocity based routing and the proposed routing algorithm is based on the number of hops to sink instead of distance. Furthermore, an acknowledgement control scheme reduces energy consumption...
In the recent years, the Ad-Hoc networks have been the focus of many researches especially in the routing protocols which include Proactive and Reactive routing. The strategy of forwarding the data packets from the source to the destination is the ultimate goal of routing protocols. Hence, the difference between these protocols is based on searching, maintenance and recovering the route path. The...
IEEE 802.11 specifies a Power Saving Mode (PSM) in order to save the energy consumptions of mobile hosts. Following the standard of PSM, a number of studies [1–4] further discussed the wakeup/sleep scheduling of beacon intervals based on Quorum systems so that any communication pair of hosts has common awake intervals for data exchange. However, most of them did not take into consideration the fact...
The early success of wireless sensor networks has led to a new generation of increasingly sophisticated sensor network applications, such as HP's CeNSE. These applications demand high network throughput that easily exceeds the capability of low-power 802.15.4 radios that are most commonly used in today's sensor nodes. To address this issue, this paper investigates an energy-efficient approach to supplementing...
In a large scale mobile sensor network, some coordinators may exhaust energy earlier if they are connected with excessive number of mobile nodes compared to the others. Balancing the load could stable and prolong the network lifetime, maximizes coordinators capabilities and improves net-work performance. In this paper, a mechanism to balance the coordinators' load based on the distribution of mobile...
Wireless Sensor Networks is a promising prototype of networking and computing, where a node may be self powered and individual node have the capability to sense and compute and communicate. Wireless Sensor Networks have been proposed for variety of applications such as Industrial control and monitoring and Home automation and Consumer electronics and Security and Military sensing, Asset tracking and...
In this paper, we discuss Sink-oriented Dynamic Location Service (SDLS) in wireless sensor networks. Since the data is collected by mobile sinks in sensor networks, sink and source must broadcast the information of locations to transfer data from a source node to a sink. To make source can built an efficiently forward data from a source node to a sink, we will discuss the direction of broadcasting...
Communication networks' energy consumption poses a considerable threat to the environment stability. The expansion of access networks, which constitute the main playground of the Internet backhaul, is accompanied by numerous energy inefficient devices and equipments. Passive optical networks (PONs) is a potential dominant technology on the field of access networking, hence the reduction of the consumed...
Multiple autonomous underwater vehicles (AUVs), communicating with each others in an opportunist way and through an arbitrary topology, create an ad-hoc underwater sensor network. Due to the mission in which AUVs might be employed or simply due to the drift typical of underwater scenarios, each node might be subject to movements from its initial position, leading to a variation on the network topology...
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