This document summarizes a research paper that proposes a protocol called DICHOTOMY for integrated resource discovery and scheduling in mobile ad hoc grids. The protocol allows computational tasks to be distributed among the most resourceful nodes in a mobile ad hoc network to efficiently balance workload. Evaluation of the protocol shows that it performs proper scheduling, maintains acceptable discovery efficiency in mobility scenarios, and scales well with increasing nodes.
Mobile Data Gathering with Load Balanced Clustering and Dual Data Uploading i...1crore projects
IEEE PROJECTS 2015
1 crore projects is a leading Guide for ieee Projects and real time projects Works Provider.
It has been provided Lot of Guidance for Thousands of Students & made them more beneficial in all Technology Training.
Dot Net
DOTNET Project Domain list 2015
1. IEEE based on datamining and knowledge engineering
2. IEEE based on mobile computing
3. IEEE based on networking
4. IEEE based on Image processing
5. IEEE based on Multimedia
6. IEEE based on Network security
7. IEEE based on parallel and distributed systems
Java Project Domain list 2015
1. IEEE based on datamining and knowledge engineering
2. IEEE based on mobile computing
3. IEEE based on networking
4. IEEE based on Image processing
5. IEEE based on Multimedia
6. IEEE based on Network security
7. IEEE based on parallel and distributed systems
ECE IEEE Projects 2015
1. Matlab project
2. Ns2 project
3. Embedded project
4. Robotics project
Eligibility
Final Year students of
1. BSc (C.S)
2. BCA/B.E(C.S)
3. B.Tech IT
4. BE (C.S)
5. MSc (C.S)
6. MSc (IT)
7. MCA
8. MS (IT)
9. ME(ALL)
10. BE(ECE)(EEE)(E&I)
TECHNOLOGY USED AND FOR TRAINING IN
1. DOT NET
2. C sharp
3. ASP
4. VB
5. SQL SERVER
6. JAVA
7. J2EE
8. STRINGS
9. ORACLE
10. VB dotNET
11. EMBEDDED
12. MAT LAB
13. LAB VIEW
14. Multi Sim
CONTACT US
1 CRORE PROJECTS
Door No: 214/215,2nd Floor,
No. 172, Raahat Plaza, (Shopping Mall) ,Arcot Road, Vadapalani, Chennai,
Tamin Nadu, INDIA - 600 026
Email id: 1croreprojects@gmail.com
website:1croreprojects.com
Phone : +91 97518 00789 / +91 72999 51536
Fast Data Collection with Interference and Life Time in Tree Based Wireless S...IJMER
This document discusses techniques for fast data collection in wireless sensor networks using a tree-based topology. It specifically focuses on minimizing the schedule length for aggregated convergecast (where data is aggregated at each hop) and raw-data convergecast (where packets are individually relayed to the sink).
It first considers time scheduling on a single channel, and then combines scheduling with transmission power control and multiple frequencies to further reduce interference and schedule length. It provides lower bounds on schedule length when interference is eliminated, and proposes algorithms that achieve these bounds.
Evaluation of different channel assignment methods, routing tree topologies, interference models, and their impact on schedule length is also presented. The key findings are that combining scheduling, power control,
International Journal of Engineering Research and Development (IJERD)IJERD Editor
This document presents a comparative study of flat-based/data-centric wireless sensor network (WSN) specific routing protocols. It first provides background on data-centric approaches in WSNs and discusses some popular flat-based/data-centric routing protocols, including Directed Diffusion, Minimum Cost Forwarding Algorithm (MCFA), Threshold sensitive Energy Efficient sensor Network protocol (TEEN), Adaptive Periodic Threshold sensitive Energy Efficient sensor Network protocol (APTEEN), Energy Aware Data (EAD) Centric Routing Protocol, RUMOR Routing, Sensor Protocols for Information via Negotiation (SPIN), Constrained Anisotropic Diffusion Routing (CADR), COUGAR,
A Platform for Large-Scale Grid Data Service on Dynamic High-Performance Netw...Tal Lavian Ph.D.
Data intensive Grid applications often deal with multiple terabytes and even petabytes of data. For them to be effectively deployed over distances, it is crucial that Grid infrastructures learn how to best exploit high-performance networks
(such as agile optical networks). The network footprint of these Grid applications show pronounced peaks and valleys in utilization, prompting for a radical overhaul of traditional network provisioning styles such as peak-provisioning, point-and-click or operator-assisted provisioning. A Grid stack must become capable to dynamically orchestrate a complex set of variables related to application requirements, data services, and network provisioning services, all within a rapidly and continually changing environment. Presented here is a platform that addresses some of these issues. This service platform closely integrates a set of large-scale data services with those for dynamic bandwidth allocation, through a network resource middleware service, using an OGSA-compliant interface allowing direct access by external applications. Recently, this platform has been implemented as an experimental research prototype on a unique wide area optical networking testbed incorporating state-of-the-art photonic
components. The paper, which presents initial results of research conducted on this prototype, indicates that these methods have the potential to address multiple major challenges related to data intensive applications. Given the complexities of this topic, especially where scheduling is required, only selected aspects of this platform are considered in this paper.
Adaptive Routing in Wireless Sensor Networks: QoS Optimisation for Enhanced A...M H
The document describes a new routing protocol called Route Optimization and Load-balancing (ROL) for wireless sensor networks. ROL aims to balance several objectives like prolonging network lifetime, providing timely message delivery, and improving network robustness. It uses a combination of routing metrics that can be configured according to application priorities to optimize overall network performance. Simulation results show that ROL maintains balanced cluster sizes and populations, reduces overhead, end-to-end delays, and improves data delivery ratios compared to other protocols like Mires++.
Clustering and data aggregation scheme in underwater wireless acoustic sensor...TELKOMNIKA JOURNAL
Underwater Wireless Acoustic Sensor Networks (UWASNs) are creating attentiveness in
researchers due to its wide area of applications. To extract the data from underwater and transmit to
watersurface, numerous clustering and data aggregation schemes are employed. The main objectives of
clustering and data aggregation schemes are to decrease the consumption of energy and prolong the
lifetime of the network. In this paper, we focus on initial clustering of sensor nodes based on their
geographical locations using fuzzy logic. The probability of degree of belongingness of a sensor node to its
cluster, along with number of clusters is analysed and discussed. Based on the energy and distance the
cluster head nodes are determined. Finally using using similarity function data aggregation is analysed and
discussed. The proposed scheme is simulated in MATLAB and compared with LEACH algorithm.
The simulation results indicate that the proposed scheme performs better in maximizing network lifetime
and minimizing energy consumption.
Algorithmic Construction of Optimal and Load Balanced Clusters in Wireless Se...M H
This paper proposes a clustering algorithm - Ba-lanced Minimum Radius Clustering (BMRC) - for use in large scale, distributed Wireless Sensor Networks (WSN). Cluster balancing is an intractable problem to solve in a distributed manner, and distribution is important, by reason of both avoiding specialised node vulnerability and minimising message overhead.The BMRC algorithm described here distributes several of the cluster balancing functions to the cluster-heads. In proposing this algorithm, several tentative claims have been made for it, namely that it is suitable for arbitrary number of cluster heads; that its pecifies a way to elect cluster heads and use them to create the local models; that it accomplishes optimal balanced clusters in distributed manner; that it is scalable and it uses the number-of-hops as a clustering parameter; that it is energy efficient. These claims were studied and verified by simulation.
Mobile Data Gathering with Load Balanced Clustering and Dual Data Uploading i...1crore projects
IEEE PROJECTS 2015
1 crore projects is a leading Guide for ieee Projects and real time projects Works Provider.
It has been provided Lot of Guidance for Thousands of Students & made them more beneficial in all Technology Training.
Dot Net
DOTNET Project Domain list 2015
1. IEEE based on datamining and knowledge engineering
2. IEEE based on mobile computing
3. IEEE based on networking
4. IEEE based on Image processing
5. IEEE based on Multimedia
6. IEEE based on Network security
7. IEEE based on parallel and distributed systems
Java Project Domain list 2015
1. IEEE based on datamining and knowledge engineering
2. IEEE based on mobile computing
3. IEEE based on networking
4. IEEE based on Image processing
5. IEEE based on Multimedia
6. IEEE based on Network security
7. IEEE based on parallel and distributed systems
ECE IEEE Projects 2015
1. Matlab project
2. Ns2 project
3. Embedded project
4. Robotics project
Eligibility
Final Year students of
1. BSc (C.S)
2. BCA/B.E(C.S)
3. B.Tech IT
4. BE (C.S)
5. MSc (C.S)
6. MSc (IT)
7. MCA
8. MS (IT)
9. ME(ALL)
10. BE(ECE)(EEE)(E&I)
TECHNOLOGY USED AND FOR TRAINING IN
1. DOT NET
2. C sharp
3. ASP
4. VB
5. SQL SERVER
6. JAVA
7. J2EE
8. STRINGS
9. ORACLE
10. VB dotNET
11. EMBEDDED
12. MAT LAB
13. LAB VIEW
14. Multi Sim
CONTACT US
1 CRORE PROJECTS
Door No: 214/215,2nd Floor,
No. 172, Raahat Plaza, (Shopping Mall) ,Arcot Road, Vadapalani, Chennai,
Tamin Nadu, INDIA - 600 026
Email id: 1croreprojects@gmail.com
website:1croreprojects.com
Phone : +91 97518 00789 / +91 72999 51536
Fast Data Collection with Interference and Life Time in Tree Based Wireless S...IJMER
This document discusses techniques for fast data collection in wireless sensor networks using a tree-based topology. It specifically focuses on minimizing the schedule length for aggregated convergecast (where data is aggregated at each hop) and raw-data convergecast (where packets are individually relayed to the sink).
It first considers time scheduling on a single channel, and then combines scheduling with transmission power control and multiple frequencies to further reduce interference and schedule length. It provides lower bounds on schedule length when interference is eliminated, and proposes algorithms that achieve these bounds.
Evaluation of different channel assignment methods, routing tree topologies, interference models, and their impact on schedule length is also presented. The key findings are that combining scheduling, power control,
International Journal of Engineering Research and Development (IJERD)IJERD Editor
This document presents a comparative study of flat-based/data-centric wireless sensor network (WSN) specific routing protocols. It first provides background on data-centric approaches in WSNs and discusses some popular flat-based/data-centric routing protocols, including Directed Diffusion, Minimum Cost Forwarding Algorithm (MCFA), Threshold sensitive Energy Efficient sensor Network protocol (TEEN), Adaptive Periodic Threshold sensitive Energy Efficient sensor Network protocol (APTEEN), Energy Aware Data (EAD) Centric Routing Protocol, RUMOR Routing, Sensor Protocols for Information via Negotiation (SPIN), Constrained Anisotropic Diffusion Routing (CADR), COUGAR,
A Platform for Large-Scale Grid Data Service on Dynamic High-Performance Netw...Tal Lavian Ph.D.
Data intensive Grid applications often deal with multiple terabytes and even petabytes of data. For them to be effectively deployed over distances, it is crucial that Grid infrastructures learn how to best exploit high-performance networks
(such as agile optical networks). The network footprint of these Grid applications show pronounced peaks and valleys in utilization, prompting for a radical overhaul of traditional network provisioning styles such as peak-provisioning, point-and-click or operator-assisted provisioning. A Grid stack must become capable to dynamically orchestrate a complex set of variables related to application requirements, data services, and network provisioning services, all within a rapidly and continually changing environment. Presented here is a platform that addresses some of these issues. This service platform closely integrates a set of large-scale data services with those for dynamic bandwidth allocation, through a network resource middleware service, using an OGSA-compliant interface allowing direct access by external applications. Recently, this platform has been implemented as an experimental research prototype on a unique wide area optical networking testbed incorporating state-of-the-art photonic
components. The paper, which presents initial results of research conducted on this prototype, indicates that these methods have the potential to address multiple major challenges related to data intensive applications. Given the complexities of this topic, especially where scheduling is required, only selected aspects of this platform are considered in this paper.
Adaptive Routing in Wireless Sensor Networks: QoS Optimisation for Enhanced A...M H
The document describes a new routing protocol called Route Optimization and Load-balancing (ROL) for wireless sensor networks. ROL aims to balance several objectives like prolonging network lifetime, providing timely message delivery, and improving network robustness. It uses a combination of routing metrics that can be configured according to application priorities to optimize overall network performance. Simulation results show that ROL maintains balanced cluster sizes and populations, reduces overhead, end-to-end delays, and improves data delivery ratios compared to other protocols like Mires++.
Clustering and data aggregation scheme in underwater wireless acoustic sensor...TELKOMNIKA JOURNAL
Underwater Wireless Acoustic Sensor Networks (UWASNs) are creating attentiveness in
researchers due to its wide area of applications. To extract the data from underwater and transmit to
watersurface, numerous clustering and data aggregation schemes are employed. The main objectives of
clustering and data aggregation schemes are to decrease the consumption of energy and prolong the
lifetime of the network. In this paper, we focus on initial clustering of sensor nodes based on their
geographical locations using fuzzy logic. The probability of degree of belongingness of a sensor node to its
cluster, along with number of clusters is analysed and discussed. Based on the energy and distance the
cluster head nodes are determined. Finally using using similarity function data aggregation is analysed and
discussed. The proposed scheme is simulated in MATLAB and compared with LEACH algorithm.
The simulation results indicate that the proposed scheme performs better in maximizing network lifetime
and minimizing energy consumption.
Algorithmic Construction of Optimal and Load Balanced Clusters in Wireless Se...M H
This paper proposes a clustering algorithm - Ba-lanced Minimum Radius Clustering (BMRC) - for use in large scale, distributed Wireless Sensor Networks (WSN). Cluster balancing is an intractable problem to solve in a distributed manner, and distribution is important, by reason of both avoiding specialised node vulnerability and minimising message overhead.The BMRC algorithm described here distributes several of the cluster balancing functions to the cluster-heads. In proposing this algorithm, several tentative claims have been made for it, namely that it is suitable for arbitrary number of cluster heads; that its pecifies a way to elect cluster heads and use them to create the local models; that it accomplishes optimal balanced clusters in distributed manner; that it is scalable and it uses the number-of-hops as a clustering parameter; that it is energy efficient. These claims were studied and verified by simulation.
MULTI-CLUSTER MULTI-CHANNEL SCHEDULING (MMS) ALGORITHM FOR MAXIMUM DATA COLLE...IJCNCJournal
Interference during data transmission can cause performance degradation like packet collisions in Wireless Sensor Networks (WSNs). While multi-channels available in IEEE 802.15.4 protocol standard WSN technology can be exploited to reduce interference, allocating channel and channel switching
algorithms can have a major impact on the performance of multi-channel communication. This paper presents an improved Fuzzy Logic based Cluster Formation and Cluster Head (CH) Selection algorithm with enhanced network lifetime for multi-cluster topology. The Multi-Cluster Multi-Channel Scheduling
(MMS) algorithm proposed in this paper improves the data collection by minimizing the maximum interference and collision. The presented work has developed Cluster formation and cluster head (CH) selection algorithm and Interference-free data communication by proper channel scheduled. The extensive
simulation and experimental outcomes prove that the proposed algorithm not only provides an interference-free transmission but also provides delay minimization and longevity of the network lifetime, which makes the presented algorithm suitable for energy-constrained wireless sensor networks.
An Overview of Information Extraction from Mobile Wireless Sensor NetworksM H
Information Extraction (IE) is a key research area within the field of Wireless Sensor Networks (WSNs). It has been characterised in a variety of ways, ranging from the description of its purposes, to reasonably abstract models of its processes and components. There has been only a handful of papers addressing IE over mobile WSNs directly, these dealt with individual mobility related problems as the need arises. This paper is presented as a tutorial that takes the reader from the point of identifying data about a dynamic (mobile) real world problem, relating the data back to the world from which it was collected, and finally discovering what is in the data. It covers the entire process with special emphasis on how to exploit mobility in maximising information return from a mobile WSN. We present some challenges introduced by mobility on the IE process as well as its effects on the quality of the extracted information. Finally, we identify future research directions facing the development of efficient IE approaches for WSNs in the presence of mobility.
Congestion is said to occur in the network when the resource demands exceed the capacity and packets are lost due to too much queuing in the network. During congestion, the network throughput may drop to zero and the path delay may become very high. A congestion control scheme helps the network to recover from the congestion state. In fact, security plays a vital role in Wireless Ad hoc network. This paper presents a systematic literature review to provide comprehensive and unbiased information about various current model Congestion Control conceptions, proposals, problems and solutions in Ad hoc for safety transportation. For this purpose, a total of 33 articles related to the security model in Congestion Control published between 2008 and 2013 were extracted from the most relevant scientific sources (IEEE Computer Society, ACM Digital Library, Springer Link and Science Direct). However, 18 articles were eventually analyzed due to several reasons such as relevancy and comprehensiveness of discussion presented in the articles. Using the systematic method of review, this paper succeeds to reveal the main security threats and Error control, challenges for security, security requirement in Congestion Control in Wireless Ad hoc network (CCWAN) and future research within this scope.
Abstract: Energy consumption is one of the constraints in Wireless Sensor Networks (WSNs). The routing protocols are the hot areas to address quality-of-service (QoS) related issues viz. Energy consumption, network lifetime, network scalability and packet overhead. In existing system a hybrid optimization based PEGASIS-DSR optimized routing protocol (PDORP) is presented which used cache and directional transmission concept of both proactive and reactive routing protocols. The performance of PDORP has been evaluated and the results indicated that it performs better in most significant parameters. The performance of the existing method is checked when it is evaluated and validated with the nodes which are highly dynamic in nature based on the application requirement. The current system finds the trusted nodes in the case of only static environment. To overcome the issue the proposed system is applied for dynamic WSN’s with the location frequently being changed. The PDORP-LC is applied with local caching (LC) to acquire the location information so that the path learning can be dynamic without depending on the fixed location. The proposed work is performing in dynamic environment with the dynamic derivation of trusted nodes.
Keywords: local caching (LC), Wireless Sensor Networks (WSNs), PEGASIS-DSR optimized routing protocol (PDORP).
Title: Energy Efficient Optimal Paths Using PDORP-LC
Author: ADARSH KUMAR B, BIBIN CHRISTOPHER, ISSAC SAJAN, AJ DEEPA
ISSN 2350-1022
International Journal of Recent Research in Mathematics Computer Science and Information Technology
Paper Publications
Simulation Issues in Wireless Sensor Networks: A SurveyM H
This paper presents a survey of simulation tools and systems for wireless sensor networks. Wireless sensor network modelling and simulation methodologies are presented for each system alongside judgments concerning their relative ease of use and accuracy. Finally, we propose a mixed-mode simulation methodology that integrates a simulated environment with real wireless sensor network testbed hardware in order to improve both the accuracy and scalability of results when evaluating different prototype designs and systems.
This document summarizes a research paper on developing an improved LEACH (Low-Energy Adaptive Clustering Hierarchy) communication protocol for energy efficient data mining in multi-feature sensor networks. It begins with background on wireless sensor networks and issues like energy efficiency. It then discusses the existing LEACH protocol and its drawbacks. The proposed improved LEACH protocol includes cluster heads, sub-cluster heads, and cluster nodes to address LEACH's limitations. This new version aims to minimize energy consumption during cluster formation and data aggregation in multi-feature sensor networks.
Information extraction from sensor networks using the Watershed transform alg...M H
Wireless sensor networks are an effective tool to provide fine resolution monitoring of the physical environment. Sensors generate continuous streams of data, which leads to several computational challenges. As sensor nodes become increasingly active devices, with more processing and communication resources, various methods of distributed data processing and sharing become feasible. The challenge is to extract information from the gathered sensory data with a specified level of accuracy in a timely and power-efficient approach. This paper presents a new solution to distributed information extraction that makes use of the morphological Watershed algorithm. The Watershed algorithm dynamically groups sensor nodes into homogeneous network segments with respect to their topological relationships and their sensing-states. This setting allows network programmers to manipulate groups of spatially distributed data streams instead of individual nodes. This is achieved by using network segments as programming abstractions on which various query processes can be executed. Aiming at this purpose, we present a reformulation of the global Watershed algorithm. The modified Watershed algorithm is fully asynchronous, where sensor nodes can autonomously process their local data in parallel and in collaboration with neighbouring nodes. Experimental evaluation shows that the presented solution is able to considerably reduce query resolution cost without scarifying the quality of the returned results. When compared to similar purpose schemes, such as “Logical Neighborhood”, the proposed approach reduces the total query resolution overhead by up to 57.5%, reduces the number of nodes involved in query resolution by up to 59%, and reduces the setup convergence time by up to 65.1%.
This document summarizes a research paper that proposes a new density-based clustering technique called Triangle-Density Based Clustering Technique (TDCT) to efficiently cluster large spatial datasets. TDCT uses a polygon approach where the number of data points inside each triangle of a polygon is calculated to determine triangle densities. Triangle densities are used to identify clusters based on a density confidence threshold. The technique aims to identify clusters of arbitrary shapes and densities while minimizing computational costs. Experimental results demonstrate the technique's superiority in terms of cluster quality and complexity compared to other density-based clustering algorithms.
The document proposes a Modified Pure Radix Sort algorithm for large heterogeneous datasets. The algorithm divides the data into numeric and string processes that work simultaneously. The numeric process further divides data into sublists by element length and sorts them simultaneously using an even/odd logic across digits. The string process identifies common patterns to convert strings to numbers that are then sorted. This optimizes problems with traditional radix sort through a distributed computing approach.
Review on Clustering and Data Aggregation in Wireless Sensor NetworkEditor IJCATR
This document provides a review of clustering and data aggregation techniques in wireless sensor networks. It begins with an introduction to wireless sensor networks and their characteristics. It then discusses clustering, which involves grouping sensor nodes into clusters headed by cluster heads. Different clustering models are described, including hierarchical clustering. The document also reviews data aggregation techniques, which aim to reduce data redundancy and save energy. It outlines common data aggregation protocols for flat and hierarchical network architectures, such as cluster-based, chain-based, tree-based and grid-based approaches. Finally, it summarizes key clustering routing protocols and data aggregation algorithms.
THRESHOLD BASED VM PLACEMENT TECHNIQUE FOR LOAD BALANCED RESOURCE PROVISIONIN...IJCNCJournal
The unbalancing load issue is a multi-variation, multi-imperative issue that corrupts the execution and productivity of processing assets. Workload adjusting methods give solutions of load unbalancing circumstances for two bothersome aspects over-burdening and under-stacking. Cloud computing utilizes planning and workload balancing for a virtualized environment, resource partaking in cloud foundation. These two factors must be handled in an improved way in cloud computing to accomplish ideal resource sharing. Henceforth, there requires productive resource, asset reservation for guaranteeing load advancement in the cloud. This work aims to present an incorporated resource, asset reservation, and workload adjusting calculation for effective cloud provisioning. The strategy develops a Priority-based Resource Scheduling Model to acquire the resource, asset reservation with threshold-based load balancing for improving the proficiency in cloud framework. Extending utilization of Virtual Machines through the suitable and sensible outstanding task at hand modifying is then practiced by intensely picking a job from submitting jobs using Priority-based Resource Scheduling Model to acquire resource asset reservation. Experimental evaluations represent, the proposed scheme gives better results by reducing execution time, with minimum resource cost and improved resource utilization in dynamic resource provisioning conditions.
Congestion Control Clustering a Review PaperEditor IJCATR
Wireless Sensor Networks consists of sensor nodes which are scattered in the environment, gather data and transmit it to a
base station for processing. Energy conservation in the Wireless Sensor Networks (WSN) is a very important task because of their
limited battery power. The related works so far have been done have tried to solve the problem keeping in the mind the constraints of
WSNs. In this paper, a priority based application specific congestion control clustering (PASCCC) protocol has been studied, which
often integrates the range of motion and heterogeneity of the nodes to detect congestion in a very network. Moreover a comparison of
the various clustering techniques has been done. From the survey it has been found that none of the protocol is efficient for energy
conservation. Hence the paper ends with future scope to overcome these issues.
Clustering-based Analysis for Heavy-Hitter Flow DetectionAPNIC
This document summarizes a research paper that proposes using unsupervised machine learning clustering techniques rather than thresholds to detect heavy hitter (HH) flows in a network. It describes collecting network flow data and analyzing it using algorithms like K-means and Gaussian mixtures to group flows. This identified multiple clusters rather than just two groups (elephants and mice). Further clustering an ambiguous zone revealed patterns that could better classify HH flows without relying on thresholds. The clustering results were then passed to an SDN controller to mark flows and take appropriate actions like re-routing.
The document proposes a clustering-based approach to dynamically allocate bandwidth in wireless networks. It extracts student data from a university's course timetable to predict user distributions over time. It then applies K-means clustering to group buildings into wireless nodes based on expected user loads. This clusters student devices and allows wireless nodes to adapt their bandwidth allocation according to predicted user demands at different times. The approach is tested on a university campus network, extracting student data to predict building loads and applying K-means clustering to allocate optimal bandwidth across wireless nodes over time.
Information Extraction from Wireless Sensor Networks: System and ApproachesM H
Recent advances in wireless communication have made it possible to develop low-cost, and low power Wireless Sensor Networks (WSN). The WSN can be used for several application areas (e.g., habitat monitoring, forest fire detection, and health care). WSN Information Extraction (IE) techniques can be classified into four categories depending on the factors that drive data acquisition: event-driven, time-driven, query-based, and hybrid. This paper presents a survey of the state-of-the-art IE techniques in WSNs. The benefits and shortcomings of different IE approaches are presented as motivation for future work into automatic hybridization and adaptation of IE mechanisms.
Efficient and Optimal Routing Scheme for Wireless Sensor Networkspaperpublications3
Abstract: The Wireless Sensor Networks (WSNs) have emerged as a new category of networking systems with limited computing, communication, and storage resources. In many sensing applications source nodes deliver packets to sink nodes via multiple hops, leading to the problem on how to find routes that enable all packets to be delivered in required time frames, while simultaneously taking into account factors such as energy efficiency and load balancing. To solve this problem one data collection protocol is developed called EDAL, which stands for Energy-efficient Delay-aware Lifetime-balancing data collection. Methods used are centralized heuristic and ant colony gossiping to find best energy efficient path. Then integrate EDAL with compressive sensing to reduce the amount of traffic generated and to reduce delay in the network.
Dynamic selection of cluster head in in networks for energy managementeSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Dynamic selection of cluster head in in networks for energy managementeSAT Journals
Abstract In this project, we presented Multipath Region Routing (MRR) protocol for energy conservation in Wireless Sensor Networks (WSNs). Large scale dense WSNs are used in different types of applications for accurate monitoring. Energy conservation is an important issue in WSNs. In order to save energy, Multipath Region Routing protocol is used which provides balance in energy consumption and sustains the network life-span. By using this method, we can reduce the number of energy dissipation because the cluster head will collect data directly from other nodes. Hence, the energy can be preserved and network life time is extended to reasonable time. Keywords: Clustering; Wireless Sensor Networks; Security; Multipath Region Routing;
Analysis and overview of Flooding Attack in Optimized link State Routing prot...IJESM JOURNAL
During this last decade, mesh networks have experienced strong growth due to their ability to provide an additional and complementary support for existing infrastructure communication systems. In such a network, routers are supposed to be fixed for short (e.g. public safety deployment) or long (e.g. network operator extension) period. This relative stability of infrastructure makes proactive routing protocols appropriate. One of the well known proactive routing protocols is OLSR (Optimized Link State Routing), which routing decisions are based on exchanges of topology information using all-to-all flooding of local information in order for each router to build a global knowledge of the topology. This study first goal is to improve the performance of topology information flooding in OLSR by introducing network coding techniques, which leads to a decrease of signaling overhead.
Interpolation Techniques for Building a Continuous Map from Discrete Wireless...M H
Wireless sensor networks (WSNs) typically gather data at a discrete number of locations. However, it is desirable to be able to design applications and reason about the data in more abstract forms than in points of data. By bestowing the ability to predict inter-node values upon the network, it is proposed that it will become possible to build applications that are unaware of the concrete reality of sparse data. This interpolation capability is realised as a service of the network. In this paper, the ‘map’ style of presentation has been identified as a suitable sense data visualisation format. Although map generation is essentially a problem of interpolation between points, a new WSN service, called the map generation service, which is based on a Shepard interpolation method, is presented. A modified Shepard method that aims to deal with the special characteristics of WSNs is proposed. It requires small storage, can be localised and integrates the information about the application domain to further reduce the map generation cost and improve the mapping accuracy. Flood management application is considered to demonstrate how MGS-generated maps can be used in various applications. Empirical analysis has shown that the map generation service is an accurate, a flexible and an efficient method.
The document discusses various applications for screening buckets, including:
1) Topsoil preparation by screening out stones and debris to produce clean, high-quality topsoil.
2) Padding pipeline and cable excavations by screening material on-site for padding, saving on transport and material costs.
3) Composting by grinding and screening raw materials and mature compost to produce a homogenous final product.
4) Industrial applications like grinding and classifying chemicals or fertilizers.
5) Screening peat moss to remove stones and debris.
6) Recycling applications like separating materials for further processing.
Este documento resume conceptos clave sobre valores sociales como el civismo, la democracia y la anomia. El civismo se refiere al comportamiento y convivencia social basados en el respeto mutuo y las normas. La democracia es un sistema de gobierno en el que el poder emana del pueblo a través de elecciones. La anomia surge de la falta de normas sociales o su ruptura, lo que puede generar una situación de caos.
MULTI-CLUSTER MULTI-CHANNEL SCHEDULING (MMS) ALGORITHM FOR MAXIMUM DATA COLLE...IJCNCJournal
Interference during data transmission can cause performance degradation like packet collisions in Wireless Sensor Networks (WSNs). While multi-channels available in IEEE 802.15.4 protocol standard WSN technology can be exploited to reduce interference, allocating channel and channel switching
algorithms can have a major impact on the performance of multi-channel communication. This paper presents an improved Fuzzy Logic based Cluster Formation and Cluster Head (CH) Selection algorithm with enhanced network lifetime for multi-cluster topology. The Multi-Cluster Multi-Channel Scheduling
(MMS) algorithm proposed in this paper improves the data collection by minimizing the maximum interference and collision. The presented work has developed Cluster formation and cluster head (CH) selection algorithm and Interference-free data communication by proper channel scheduled. The extensive
simulation and experimental outcomes prove that the proposed algorithm not only provides an interference-free transmission but also provides delay minimization and longevity of the network lifetime, which makes the presented algorithm suitable for energy-constrained wireless sensor networks.
An Overview of Information Extraction from Mobile Wireless Sensor NetworksM H
Information Extraction (IE) is a key research area within the field of Wireless Sensor Networks (WSNs). It has been characterised in a variety of ways, ranging from the description of its purposes, to reasonably abstract models of its processes and components. There has been only a handful of papers addressing IE over mobile WSNs directly, these dealt with individual mobility related problems as the need arises. This paper is presented as a tutorial that takes the reader from the point of identifying data about a dynamic (mobile) real world problem, relating the data back to the world from which it was collected, and finally discovering what is in the data. It covers the entire process with special emphasis on how to exploit mobility in maximising information return from a mobile WSN. We present some challenges introduced by mobility on the IE process as well as its effects on the quality of the extracted information. Finally, we identify future research directions facing the development of efficient IE approaches for WSNs in the presence of mobility.
Congestion is said to occur in the network when the resource demands exceed the capacity and packets are lost due to too much queuing in the network. During congestion, the network throughput may drop to zero and the path delay may become very high. A congestion control scheme helps the network to recover from the congestion state. In fact, security plays a vital role in Wireless Ad hoc network. This paper presents a systematic literature review to provide comprehensive and unbiased information about various current model Congestion Control conceptions, proposals, problems and solutions in Ad hoc for safety transportation. For this purpose, a total of 33 articles related to the security model in Congestion Control published between 2008 and 2013 were extracted from the most relevant scientific sources (IEEE Computer Society, ACM Digital Library, Springer Link and Science Direct). However, 18 articles were eventually analyzed due to several reasons such as relevancy and comprehensiveness of discussion presented in the articles. Using the systematic method of review, this paper succeeds to reveal the main security threats and Error control, challenges for security, security requirement in Congestion Control in Wireless Ad hoc network (CCWAN) and future research within this scope.
Abstract: Energy consumption is one of the constraints in Wireless Sensor Networks (WSNs). The routing protocols are the hot areas to address quality-of-service (QoS) related issues viz. Energy consumption, network lifetime, network scalability and packet overhead. In existing system a hybrid optimization based PEGASIS-DSR optimized routing protocol (PDORP) is presented which used cache and directional transmission concept of both proactive and reactive routing protocols. The performance of PDORP has been evaluated and the results indicated that it performs better in most significant parameters. The performance of the existing method is checked when it is evaluated and validated with the nodes which are highly dynamic in nature based on the application requirement. The current system finds the trusted nodes in the case of only static environment. To overcome the issue the proposed system is applied for dynamic WSN’s with the location frequently being changed. The PDORP-LC is applied with local caching (LC) to acquire the location information so that the path learning can be dynamic without depending on the fixed location. The proposed work is performing in dynamic environment with the dynamic derivation of trusted nodes.
Keywords: local caching (LC), Wireless Sensor Networks (WSNs), PEGASIS-DSR optimized routing protocol (PDORP).
Title: Energy Efficient Optimal Paths Using PDORP-LC
Author: ADARSH KUMAR B, BIBIN CHRISTOPHER, ISSAC SAJAN, AJ DEEPA
ISSN 2350-1022
International Journal of Recent Research in Mathematics Computer Science and Information Technology
Paper Publications
Simulation Issues in Wireless Sensor Networks: A SurveyM H
This paper presents a survey of simulation tools and systems for wireless sensor networks. Wireless sensor network modelling and simulation methodologies are presented for each system alongside judgments concerning their relative ease of use and accuracy. Finally, we propose a mixed-mode simulation methodology that integrates a simulated environment with real wireless sensor network testbed hardware in order to improve both the accuracy and scalability of results when evaluating different prototype designs and systems.
This document summarizes a research paper on developing an improved LEACH (Low-Energy Adaptive Clustering Hierarchy) communication protocol for energy efficient data mining in multi-feature sensor networks. It begins with background on wireless sensor networks and issues like energy efficiency. It then discusses the existing LEACH protocol and its drawbacks. The proposed improved LEACH protocol includes cluster heads, sub-cluster heads, and cluster nodes to address LEACH's limitations. This new version aims to minimize energy consumption during cluster formation and data aggregation in multi-feature sensor networks.
Information extraction from sensor networks using the Watershed transform alg...M H
Wireless sensor networks are an effective tool to provide fine resolution monitoring of the physical environment. Sensors generate continuous streams of data, which leads to several computational challenges. As sensor nodes become increasingly active devices, with more processing and communication resources, various methods of distributed data processing and sharing become feasible. The challenge is to extract information from the gathered sensory data with a specified level of accuracy in a timely and power-efficient approach. This paper presents a new solution to distributed information extraction that makes use of the morphological Watershed algorithm. The Watershed algorithm dynamically groups sensor nodes into homogeneous network segments with respect to their topological relationships and their sensing-states. This setting allows network programmers to manipulate groups of spatially distributed data streams instead of individual nodes. This is achieved by using network segments as programming abstractions on which various query processes can be executed. Aiming at this purpose, we present a reformulation of the global Watershed algorithm. The modified Watershed algorithm is fully asynchronous, where sensor nodes can autonomously process their local data in parallel and in collaboration with neighbouring nodes. Experimental evaluation shows that the presented solution is able to considerably reduce query resolution cost without scarifying the quality of the returned results. When compared to similar purpose schemes, such as “Logical Neighborhood”, the proposed approach reduces the total query resolution overhead by up to 57.5%, reduces the number of nodes involved in query resolution by up to 59%, and reduces the setup convergence time by up to 65.1%.
This document summarizes a research paper that proposes a new density-based clustering technique called Triangle-Density Based Clustering Technique (TDCT) to efficiently cluster large spatial datasets. TDCT uses a polygon approach where the number of data points inside each triangle of a polygon is calculated to determine triangle densities. Triangle densities are used to identify clusters based on a density confidence threshold. The technique aims to identify clusters of arbitrary shapes and densities while minimizing computational costs. Experimental results demonstrate the technique's superiority in terms of cluster quality and complexity compared to other density-based clustering algorithms.
The document proposes a Modified Pure Radix Sort algorithm for large heterogeneous datasets. The algorithm divides the data into numeric and string processes that work simultaneously. The numeric process further divides data into sublists by element length and sorts them simultaneously using an even/odd logic across digits. The string process identifies common patterns to convert strings to numbers that are then sorted. This optimizes problems with traditional radix sort through a distributed computing approach.
Review on Clustering and Data Aggregation in Wireless Sensor NetworkEditor IJCATR
This document provides a review of clustering and data aggregation techniques in wireless sensor networks. It begins with an introduction to wireless sensor networks and their characteristics. It then discusses clustering, which involves grouping sensor nodes into clusters headed by cluster heads. Different clustering models are described, including hierarchical clustering. The document also reviews data aggregation techniques, which aim to reduce data redundancy and save energy. It outlines common data aggregation protocols for flat and hierarchical network architectures, such as cluster-based, chain-based, tree-based and grid-based approaches. Finally, it summarizes key clustering routing protocols and data aggregation algorithms.
THRESHOLD BASED VM PLACEMENT TECHNIQUE FOR LOAD BALANCED RESOURCE PROVISIONIN...IJCNCJournal
The unbalancing load issue is a multi-variation, multi-imperative issue that corrupts the execution and productivity of processing assets. Workload adjusting methods give solutions of load unbalancing circumstances for two bothersome aspects over-burdening and under-stacking. Cloud computing utilizes planning and workload balancing for a virtualized environment, resource partaking in cloud foundation. These two factors must be handled in an improved way in cloud computing to accomplish ideal resource sharing. Henceforth, there requires productive resource, asset reservation for guaranteeing load advancement in the cloud. This work aims to present an incorporated resource, asset reservation, and workload adjusting calculation for effective cloud provisioning. The strategy develops a Priority-based Resource Scheduling Model to acquire the resource, asset reservation with threshold-based load balancing for improving the proficiency in cloud framework. Extending utilization of Virtual Machines through the suitable and sensible outstanding task at hand modifying is then practiced by intensely picking a job from submitting jobs using Priority-based Resource Scheduling Model to acquire resource asset reservation. Experimental evaluations represent, the proposed scheme gives better results by reducing execution time, with minimum resource cost and improved resource utilization in dynamic resource provisioning conditions.
Congestion Control Clustering a Review PaperEditor IJCATR
Wireless Sensor Networks consists of sensor nodes which are scattered in the environment, gather data and transmit it to a
base station for processing. Energy conservation in the Wireless Sensor Networks (WSN) is a very important task because of their
limited battery power. The related works so far have been done have tried to solve the problem keeping in the mind the constraints of
WSNs. In this paper, a priority based application specific congestion control clustering (PASCCC) protocol has been studied, which
often integrates the range of motion and heterogeneity of the nodes to detect congestion in a very network. Moreover a comparison of
the various clustering techniques has been done. From the survey it has been found that none of the protocol is efficient for energy
conservation. Hence the paper ends with future scope to overcome these issues.
Clustering-based Analysis for Heavy-Hitter Flow DetectionAPNIC
This document summarizes a research paper that proposes using unsupervised machine learning clustering techniques rather than thresholds to detect heavy hitter (HH) flows in a network. It describes collecting network flow data and analyzing it using algorithms like K-means and Gaussian mixtures to group flows. This identified multiple clusters rather than just two groups (elephants and mice). Further clustering an ambiguous zone revealed patterns that could better classify HH flows without relying on thresholds. The clustering results were then passed to an SDN controller to mark flows and take appropriate actions like re-routing.
The document proposes a clustering-based approach to dynamically allocate bandwidth in wireless networks. It extracts student data from a university's course timetable to predict user distributions over time. It then applies K-means clustering to group buildings into wireless nodes based on expected user loads. This clusters student devices and allows wireless nodes to adapt their bandwidth allocation according to predicted user demands at different times. The approach is tested on a university campus network, extracting student data to predict building loads and applying K-means clustering to allocate optimal bandwidth across wireless nodes over time.
Information Extraction from Wireless Sensor Networks: System and ApproachesM H
Recent advances in wireless communication have made it possible to develop low-cost, and low power Wireless Sensor Networks (WSN). The WSN can be used for several application areas (e.g., habitat monitoring, forest fire detection, and health care). WSN Information Extraction (IE) techniques can be classified into four categories depending on the factors that drive data acquisition: event-driven, time-driven, query-based, and hybrid. This paper presents a survey of the state-of-the-art IE techniques in WSNs. The benefits and shortcomings of different IE approaches are presented as motivation for future work into automatic hybridization and adaptation of IE mechanisms.
Efficient and Optimal Routing Scheme for Wireless Sensor Networkspaperpublications3
Abstract: The Wireless Sensor Networks (WSNs) have emerged as a new category of networking systems with limited computing, communication, and storage resources. In many sensing applications source nodes deliver packets to sink nodes via multiple hops, leading to the problem on how to find routes that enable all packets to be delivered in required time frames, while simultaneously taking into account factors such as energy efficiency and load balancing. To solve this problem one data collection protocol is developed called EDAL, which stands for Energy-efficient Delay-aware Lifetime-balancing data collection. Methods used are centralized heuristic and ant colony gossiping to find best energy efficient path. Then integrate EDAL with compressive sensing to reduce the amount of traffic generated and to reduce delay in the network.
Dynamic selection of cluster head in in networks for energy managementeSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Dynamic selection of cluster head in in networks for energy managementeSAT Journals
Abstract In this project, we presented Multipath Region Routing (MRR) protocol for energy conservation in Wireless Sensor Networks (WSNs). Large scale dense WSNs are used in different types of applications for accurate monitoring. Energy conservation is an important issue in WSNs. In order to save energy, Multipath Region Routing protocol is used which provides balance in energy consumption and sustains the network life-span. By using this method, we can reduce the number of energy dissipation because the cluster head will collect data directly from other nodes. Hence, the energy can be preserved and network life time is extended to reasonable time. Keywords: Clustering; Wireless Sensor Networks; Security; Multipath Region Routing;
Analysis and overview of Flooding Attack in Optimized link State Routing prot...IJESM JOURNAL
During this last decade, mesh networks have experienced strong growth due to their ability to provide an additional and complementary support for existing infrastructure communication systems. In such a network, routers are supposed to be fixed for short (e.g. public safety deployment) or long (e.g. network operator extension) period. This relative stability of infrastructure makes proactive routing protocols appropriate. One of the well known proactive routing protocols is OLSR (Optimized Link State Routing), which routing decisions are based on exchanges of topology information using all-to-all flooding of local information in order for each router to build a global knowledge of the topology. This study first goal is to improve the performance of topology information flooding in OLSR by introducing network coding techniques, which leads to a decrease of signaling overhead.
Interpolation Techniques for Building a Continuous Map from Discrete Wireless...M H
Wireless sensor networks (WSNs) typically gather data at a discrete number of locations. However, it is desirable to be able to design applications and reason about the data in more abstract forms than in points of data. By bestowing the ability to predict inter-node values upon the network, it is proposed that it will become possible to build applications that are unaware of the concrete reality of sparse data. This interpolation capability is realised as a service of the network. In this paper, the ‘map’ style of presentation has been identified as a suitable sense data visualisation format. Although map generation is essentially a problem of interpolation between points, a new WSN service, called the map generation service, which is based on a Shepard interpolation method, is presented. A modified Shepard method that aims to deal with the special characteristics of WSNs is proposed. It requires small storage, can be localised and integrates the information about the application domain to further reduce the map generation cost and improve the mapping accuracy. Flood management application is considered to demonstrate how MGS-generated maps can be used in various applications. Empirical analysis has shown that the map generation service is an accurate, a flexible and an efficient method.
The document discusses various applications for screening buckets, including:
1) Topsoil preparation by screening out stones and debris to produce clean, high-quality topsoil.
2) Padding pipeline and cable excavations by screening material on-site for padding, saving on transport and material costs.
3) Composting by grinding and screening raw materials and mature compost to produce a homogenous final product.
4) Industrial applications like grinding and classifying chemicals or fertilizers.
5) Screening peat moss to remove stones and debris.
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Este documento resume conceptos clave sobre valores sociales como el civismo, la democracia y la anomia. El civismo se refiere al comportamiento y convivencia social basados en el respeto mutuo y las normas. La democracia es un sistema de gobierno en el que el poder emana del pueblo a través de elecciones. La anomia surge de la falta de normas sociales o su ruptura, lo que puede generar una situación de caos.
In this two part session, Devora Steinmetz explores the goals of Mishna study in elementary school; addresses how to select texts to teach to children; demonstrates presenting Mishna in a broader context; suggests strategies for teaching. Dr. Devora Steinmetz is the founder of Beit Rabban, a day school and center for educational research in New York City. She is the author of From Father to Son: Kinship, Conflict, and Continuity in Genesis and of articles on biblical and rabbinic texts. Dr. Steinmetz is currently Assistant Professor of Talmud and Rabbinics at the Jewish Theological Seminary.
Lymphatic And Immune Systems by Myrtle AcreeMyrtle Acree
The lymphatic system circulates lymph fluid throughout the body and contains immune cells called lymphocytes that protect the body from pathogens. The immune system defends the body from infectious organisms through special cells, proteins, tissues, and organs. Together, the lymphatic and immune systems work to maintain fluid balance, produce immune cells, absorb lipids, and protect the body from disease.
La contabilidad estudia, mide y analiza la situación económica y financiera de las organizaciones para facilitar su dirección y control. Suministra información sobre los resultados obtenidos y la situación patrimonial en un momento dado, lo que resulta útil para la toma de decisiones. La contabilidad es una técnica que se basa en procedimientos para acumular y procesar datos sobre el patrimonio de una entidad, y también es considerada como un subsistema de información.
The document is a summary of a student's resume highlighting their experience as a warehouse manager for Habitat for Humanity, minoring in French with professional fluency, receiving an expert witness award in undergraduate mock trial, researching food policy through a university seminar program, volunteering with a college bound program, majoring in entrepreneurship and business analytics at Indiana University's business school, and being elected to the IU student government congress.
The document outlines different types of procedural, report, and narrative texts. It provides examples of procedural texts that explain how to use various devices and instructions for activities. Report texts are described as responding to topics or identifying characteristics through reports, graphics, or letters. Narrative texts are defined as stories with correct punctuation and pauses or identifying structures through legends. A variety of examples are given for each text type.
Curso mei 787 fundamentos de la energía eléctricaProcasecapacita
Este documento presenta los objetivos, temario y duración de un curso sobre los fundamentos de la energía eléctrica. El curso busca que los participantes dominen conceptos básicos como voltaje, corriente y resistencia, así como también entiendan los procesos de generación, transmisión y consumo de energía eléctrica. El temario cubre alternativas de ahorro energético, dimensionamiento de conductores, transformadores, regulación de voltaje y uso de instrumentos de medición. El curso dura 24 horas y usa un manual como material did
2. Labour market supply, demand, innovation, investmentistituto manzoni
This document discusses labor markets and the factors that impact supply and demand for labor. It defines a labor market as a market where people offer their skills in exchange for compensation like wages. The labor market reaches equilibrium when the supply of labor equals the demand. Technological advances are changing the types of jobs available, increasing demand for skills that complement new technologies while putting low-skilled jobs at risk. Investing in education, training, factories and machinery can raise future living standards by increasing productivity and wages. Firms provide both general and specific job training to workers.
In this two part session, Devora Steinmetz explores the goals of Mishna study in elementary school; addresses how to select texts to teach to children; demonstrates presenting Mishna in a broader context; suggests strategies for teaching. Dr. Devora Steinmetz is the founder of Beit Rabban, a day school and center for educational research in New York City. She is the author of From Father to Son: Kinship, Conflict, and Continuity in Genesis and of articles on biblical and rabbinic texts. Dr. Steinmetz is currently Assistant Professor of Talmud and Rabbinics at the Jewish Theological Seminary.
Labour Supply and Demand Issues in BC Education SectroAndrew Jang
Make a Future has been a leader over the past four years in the area of labour market analysis of the K-12 Public Education Sector. This slideshow provides an overview of these efforts.
Voluntry councelling and testing by dr munawar khanDr Munawar Khan
Voluntary Counseling and Testing (VCT) involves providing counseling to individuals to assess their HIV risk, discuss testing and developing a risk reduction plan, and provides testing to help people learn their HIV status so they can receive medical care and support services if needed, though many people face barriers to testing like fear, stigma, and lack of perceived benefits.
Professor
Department of Community Medicine
J.N. Medical College, Aligarh Muslim University, Aligarh
Sexually transmitted infections (STIs) are infections that are spread primarily through person-to-person sexual contact. Some of the most common STIs include chlamydia, gonorrhea, syphilis, and trichomoniasis. Human papillomavirus (HPV) infection is also considered an STI. STIs are a major public health problem worldwide. They can cause serious, permanent damage to a person's reproductive and other systems if not treated. Some STIs may also increase the risk of acquiring or transmitting HIV. STIs are preventable through safe sexual practices and regular screening
The document discusses three key issues in macroeconomics: (1) price and wage flexibility, (2) flexibility of aggregate supply, and (3) the role of expectations. It then provides an overview of classical macroeconomics, Keynesian economics, the monetarist-Keynesian debate, and the current range of macroeconomic views.
The document describes the evolution and components of India's National AIDS Control Program (NACP). It began in 1992 and is now in its fourth phase (NACP-IV) from 2012-2017. Key aspects include:
- Integrated Counselling and Testing Centers (ICTCs) were established in 2006 by integrating earlier Voluntary Counselling and Testing Centers (VCTCs) and Prevention of Parent-to-Child Transmission centers.
- NACP-IV has 5 components: prevention services, expanding information/education, comprehensive care/support/treatment, strengthening institutional capacities, and a strategic information management system.
- Targeted interventions provide prevention, care, and treatment services focused on high-
Review on Analysis of Latency of Stateless Opportunistic Forwarding in Interm...IRJET Journal
This document summarizes research on analyzing the latency of stateless opportunistic forwarding in intermittently connected networks. It begins with an abstract that discusses using random walks to model packet forwarding in these networks and estimating end-to-end delay. The introduction then provides background on using stateless opportunistic forwarding with random walk-based routing in disconnected networks. Several related works are discussed that examine using random walks for data collection in sensor networks, modeling delay in opportunistic forwarding networks, and analyzing properties of random walks on dynamic graphs. The conclusion discusses how this approach can achieve reliable delivery ratios with low overhead in intermittently connected networks.
AN ENTROPIC OPTIMIZATION TECHNIQUE IN HETEROGENEOUS GRID COMPUTING USING BION...ijcsit
This document summarizes a research paper that proposes a new method for improving both fault tolerance and load balancing in grid computing networks. The method converts the tree structure of grid computing nodes into a distributed R-tree index structure and then applies an entropy estimation technique. This entropy estimation helps discard nodes with high entropy from the tree, reducing complexity. The method then uses thresholding and control algorithms to select optimal route paths based on load balance and fault tolerance. Various optimization techniques like genetic algorithms, ant colony optimization, and particle swarm optimization are also applied to reach better solutions. Experimental results showed the proposed method improved performance over other existing methods.
In network aggregation techniques for wireless sensor networks - a surveyGungi Achi
This document provides a comprehensive survey of in-network aggregation techniques for wireless sensor networks. It begins by defining in-network aggregation and classifying approaches into those with and without data size reduction. It identifies the key components of in-network aggregation as routing protocols, aggregation functions, and data representation. It reviews theoretical limits of aggregation and discusses open issues. The document aims to provide an updated view of in-network aggregation and motivate future research in this area.
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MULTIDIMENSIONAL ANALYSIS FOR QOS IN WIRELESS SENSOR NETWORKSijcses
Nodes in Mobile Ad-hoc network are connected wirelessly and the network is auto configuring [1]. This paper introduces the usefulness of data warehouse as an alternative to manage data collected by WSN.Wireless Sensor Network produces huge quantity of data that need to be proceeded and homogenised, so as to help researchers and other people interested in the information. Collected data is managed and compared with other coming from datasources and systems could participate in technical report and decision making. This paper proposes a model to design, extract, transform and normalize data collected by Wireless Sensor Networks by implementing a multidimensional warehouse for comparing many aspects in WSN such as (routing protocol[4], sensor, sensor mobility, cluster ….). Hence, data warehouse defined and applied to the context above is presented as a useful approach that gives specialists row data and information for decision processes and navigate from one aspect to another.
Data Warehouses store integrated and consistent data in a subject-oriented data repository dedicated
especially to support business intelligence processes. However, keeping these repositories updated usually
involves complex and time-consuming processes, commonly denominated as Extract-Transform-Load tasks.
These data intensive tasks normally execute in a limited time window and their computational requirements
tend to grow in time as more data is dealt with. Therefore, we believe that a grid environment could suit
rather well as support for the backbone of the technical infrastructure with the clear financial advantage of
using already acquired desktop computers normally present in the organization. This article proposes a
different approach to deal with the distribution of ETL processes in a grid environment, taking into account
not only the processing performance of its nodes but also the existing bandwidth to estimate the grid
availability in a near future and therefore optimize workflow distribution.
Mobile Agents based Energy Efficient Routing for Wireless Sensor NetworksEswar Publications
Energy Efficiency and prolonged network lifetime are few of the major concern areas. Energy consumption rated of sensor nodes can be reduced in various ways. Data aggregation, result sharing and filtration of aggregated data among sensor nodes deployed in the unattended regions have been few of the most researched areas in the field of wireless sensor networks. While data aggregation is concerned with minimizing the information transfer from source to sink to reduce network traffic and removing congestion in network, result sharing focuses on sharing of information among agents pertinent to the tasks at hand and filtration of aggregated data so as to remove redundant information. There exist various algorithms for data aggregation and filtration using different mobile agents. In this proposed work same mobile agent is used to perform both tasks data aggregation and data filtration. This approach advocates the sharing of resources and reducing the energy consumption level of sensor nodes.
A Professional QoS Provisioning in the Intra Cluster Packet Level Resource Al...GiselleginaGloria
Wireless mesh networking has transpired as a gifted technology for potential broadband wireless access. In a communication network, wireless mesh network plays a vital role in transmission and are structured in a mesh topology. The coordination of mesh routers and mesh clients forms the wireless mesh networks which are routed through the gateways. Wireless mesh networks uses IEEE 802.11 standards and has its wide applications broadband home networking and enterprise networking deployment such as Microsoft wireless mesh and MIT etc. A professional Qos provisioning in intra cluster packet level resource allocation for WMN approach takes power allocation, sub carrier allocation and packet scheduling. This approach combines the merits of a Karush-Kuhn-Tucker (KKT) algorithm and a genetic algorithm (GA) based approach. The KKT algorithm uses uniform power allocation over all the subcarriers, based on the optimal allocation criterion. The genetic algorithm is used to generate useful solutions to optimization and search problems and it is also used for search problems. By combining the intrinsic worth of both the approaches, it facilitates effective QOS provisioning at the packet level. It is concluded that, this approach achieves a preferred stability between system implementation and computational convolution.
IRJET- Sink Mobility based Energy Efficient Routing Protocol for Wireless Sen...IRJET Journal
The document describes a proposed sink mobility based energy efficient routing protocol for wireless sensor networks. The protocol uses both a static centralized sink and a mobile sink that follows a predetermined path with 4 sojourn locations. This is aimed to improve network lifetime by balancing energy load across nodes. Simulation results show that the proposed approach with a mobile sink performs better than the Threshold sensitive Energy Efficient sensor Network (TEEN) protocol alone in terms of number of alive nodes, number of cluster heads, and number of packets sent to the base station over multiple rounds. Using a mobile sink helps scatter the energy load in the network and extends lifetime compared to only using a static sink.
OPTIMIZED ROUTING AND DENIAL OF SERVICE FOR ROBUST TRANSMISSION IN WIRELESS N...IRJET Journal
This document proposes a system to optimize routing and prevent denial of service attacks in wireless networks. It aims to detect distributed denial of service (DDoS) attacks using a classifier system called CS_DDoS that classifies packets as malicious or normal. Malicious packets will be blocked and their IP addresses blacklisted. It also aims to use a hybrid optimization system (HOS) for efficient, quality routing to increase network lifetime and user communication. The system is designed to differentiate between genuine and malicious traffic, transfer data via alternative paths if attacks are detected, and balance network load for stable data transfer while improving packet delivery and throughput.
Amaru Plug Resilient In-Band Control For SDNJeff Brooks
Amaru is a protocol that provides plug-and-play, resilient in-band control for SDN networks. It uses an exploration mechanism to quickly find all possible paths between the controller and network nodes. Routing is based on masked MAC addresses, which simplifies routing tables to only one entry per path. Amaru was evaluated using three implementations across diverse networks and failures. It provided near instant rerouting and low recovery times.
Minimum Process Coordinated Checkpointing Scheme For Ad Hoc Networks pijans
The wireless mobile ad hoc network (MANET) architecture is one consisting of a set of mobile hosts
capable of communicating with each other without the assistance of base stations. This has made possible
creating a mobile distributed computing environment and has also brought several new challenges in
distributed protocol design. In this paper, we study a very fundamental problem, the fault tolerance
problem, in a MANET environment and propose a minimum process coordinated checkpointing scheme.
Since potential problems of this new environment are insufficient power and limited storage capacity, the
proposed scheme tries to reduce the amount of information saved for recovery. The MANET structure used
in our algorithm is hierarchical based. The scheme is based for Cluster Based Routing Protocol (CBRP)
which belongs to a class of Hierarchical Reactive routing protocols. The protocol proposed by us is nonblocking coordinated checkpointing algorithm suitable for ad hoc environments. It produces a consistent
set of checkpoints; the algorithm makes sure that only minimum number of nodes in the cluster are
required to take checkpoints; it uses very few control messages. Performance analysis shows that our
algorithm outperforms the existing related works and is a novel idea in the field. Firstly, we describe an
organization of the cluster. Then we propose a minimum process coordinated checkpointing scheme for
cluster based ad hoc routing protocols.
Our journal focused on Engineering, Management, Science and Mathematics, we broadly cover research work. our journal publishes Paper Publications, Scopus indexed journals, WoS indexed journals, research paper publications, academic journals, journal publications.
DWDM-RAM: An Architecture for Data Intensive Service Enabled by Next Generati...Tal Lavian Ph.D.
An architecture is proposed for data-intensive services enabled by next generation dynamic optical networks. The architecture supports new data communication services that allow for coordinating extremely large sets of distributed data. The architecture allows for novel features including algorithms for optimizing and scheduling data transfers,methods for allocating and scheduling network resources, and an intelligent middleware platform that is capable of interfacing application level services to the underlying optical technologies. The significance of the architecture is twofold: 1) it encapsulates “optical network resources” into a service framework to support dynamically provisioned and advance scheduled data-intensive transport services, and 2) it establishes a generalized enabling framework for intelligent services and applications over next generation networks, not necessarily optical end-to-end. DWDM-RAM1 is an implementation version of the architecture, which is conceptual as well as experimental. This architecture has been implemented in prototype on OMNInet, which is an advanced experimental metro area optical testbed that is based on novel architecture, protocols, control plane services (Optical Dynamic Intelligent Network-ODIN2), and advanced photonic components. This paper presents the concepts behind the DWDM-RAM architecture and its design. The paper also describes an application scenario using the architecture’s data transfer service and network resource services over the agile OMNInet testbed.
IoT Resource Allocation and Optimization Using Improved Reptile Search AlgorithmIJCNCJournal
The Internet of Things (IoT) is a dispersed network system that connects the world through the Internet. The architecture of IoT consists of more gateways and resources which cannot be allocated in a manual process. The allocation of resources in IoT is a challenging process due to the higher consumption of energy and high latency rate. To overcome the challenges in existing works, this research introduced an Improved Reptile Search Algorithm (IRSA) to solve the optimization problem which occurs during the time of allocation resources among IoT networks. IRSA employs the methodology of levy flight and cross-over to update the candidate position and enhance the search speed in a single iteration. The proposed method consumes less energy and has low latency during data transmission from User equipment (UE) to the base station.IRSA has been compared with the existing Scalable Resource Allocation Framework (SRAF) and Improved Chaotic Firefly Algorithm (ICFA). The obtained experimental results show that the proposed IRSA attained better performance with an allocation rate of 96.40% which is comparatively higher than SRAF and ICFA with 92.40% and 91.67% respectively.
IoT Resource Allocation and Optimization Using Improved Reptile Search AlgorithmIJCNCJournal
The Internet of Things (IoT) is a dispersed network system that connects the world through the Internet. The architecture of IoT consists of more gateways and resources which cannot be allocated in a manual process. The allocation of resources in IoT is a challenging process due to the higher consumption of energy and high latency rate. To overcome the challenges in existing works, this research introduced an Improved Reptile Search Algorithm (IRSA) to solve the optimization problem which occurs during the time of allocation resources among IoT networks. IRSA employs the methodology of levy flight and cross-over to update the candidate position and enhance the search speed in a single iteration. The proposed method consumes less energy and has low latency during data transmission from User equipment (UE) to the base station.IRSA has been compared with the existing Scalable Resource Allocation Framework (SRAF) and Improved Chaotic Firefly Algorithm (ICFA). The obtained experimental results show that the proposed IRSA attained better performance with an allocation rate of 96.40% which is comparatively higher than SRAF and ICFA with 92.40% and 91.67% respectively.
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Performance evaluation of a discovery and scheduling protocol for multihop ad hoc mobile grids
1. ISSN 0104-6500Journal of the Brazilian Computer Society, 2009; 15(4):15-29.
*e-mail: atagomes@lncc.br
Performance evaluation of a discovery and scheduling
protocol for multihop ad hoc mobile grids
Antônio Tadeu Azevedo Gomes1
*, Artur Ziviani1
, Luciana dos Santos Lima2
, Markus Endler3
1
National Laboratory for Scientific Computing – LNCC,
Av. Getúlio Vargas, 333, 25651-075, Petrópolis, RJ, Brazil
2
Nokia Siemens Networks (NSN)
Av. das Américas, 3434 - Bloco 7- 3o.
andar, 22640-102, Rio de Janeiro, RJ, Brazil
3
Pontifical Catholic University of Rio de Janeiro (PUC-Rio)
Rua Marquês de São Vicente, 225, 22453-900, Rio de Janeiro, RJ, Brazil
Received: July 10, 2009; Accepted: December 3, 2009
Abstract: Despite the many research efforts addressing the integration of mobile nodes into grids, only a few of them have
considered the establishment of mobile grids over wireless ad hoc networks (hereafter, mobile ad hoc grids). Clearly, such grids
need specialized resource discovery and scheduling mechanisms. To the best of our knowledge, though, the research on
these mechanisms for mobile ad hoc grids is still preliminary. Besides, and more importantly, it has approached discovery
and scheduling as separate mechanisms, which, we argue, is not suitable for mobile ad hoc grids. In this paper, we propose
the integration of resource discovery and scheduling for mobile ad hoc grids into a single protocol called DICHOTOMY
(DIscovery and sCHeduling prOTOcol for MobilitY). This protocol allows computational tasks to be distributed appropriately
in a mobile ad hoc grid, while mitigating the overhead of discovery messages exchanged among the nodes. Our experiments
show that the protocol: (i) does proper scheduling, allowing an efficient load balancing among the nodes and helping with
lowering the average completion time of tasks; (ii) keeps the discovery efficiency at acceptable levels in mobility scenarios and
(iii) scales very well with respect to an increasing number of nodes, both in the total amount of energy savings due to packet
transmissions and the distribution of such savings among the nodes.
Keywords: mobile grids, resource management, self-organizing networks.
1. Introduction
There has been an increasing amount of research over the
past few years on wireless grids36
. These extend traditional
grids2
by integrating mobile devices in a wireless infrastruc-
tured network as either resource consumers or providers in
the computing infrastructure. Only a few efforts31,45
, however,
have addressed the more challenging issue of dynamically
establishing spontaneous, purely mobile ad hoc grids i.e.
grids established over mobile ad hoc networks, and even
these have achieved only preliminary results. Further devel-
opment in mobile ad hoc grids can be justified by some
applications that demand high computational power but at
the same time have to be used at places or conditions where
network infrastructure may be or may suddenly become
unavailable21
. In particular, we focus on application scenarios
in which the mobility of devices is constrained to pedestrian
(walking) speeds. Examples of such scenarios include:
• Emergency response systems for disaster handling and
crisis management situations. For instance, consider
a large rescue and medical team working in a natural
disaster scenario, such as the one caused by the Indian
Ocean tsunami in Dec. 2004 or the hurricane Katrina
that hit New Orleans in Aug. 2005. In such scenarios,
the seamless integration of computational resources
from on-site mobile nodes can be crucial for rapidly
achieving advanced forms of collaborative work, as
for example to collect and automatically process infor-
mation about groups of injured people (e.g. for triage)
and thus better allocate rescue teams and medical
resources13
. In this context, mobile ad hoc grids can
be regarded as specializations of the more general
concept of hastily formed networks9
.
• Field research systems dynamically deployed on isolated
areas. For instance, consider a team of hydrogeolo-
gists throughout a large semi-arid region, such as the
Northeastern Brazil. Such a team can exchange data
about underground water resources (e.g. hydraulic
head) being collected by their mobile nodes, and
may use the computational resources of such nodes
for in-loco, preliminary numerical analysis on the
collected data, so as to simulate and predict some
aquifer condition of interest (e.g. the effect of irriga-
tion developments).
Both aforementioned application scenarios demand the
formation of multihop mobile ad hoc networks (hereafter,
2. Journal of the Brazilian Computer Society16 Gomes ATA et al.
MANETs). MANETs allow mobile nodes to self-organize
into arbitrary and temporary topologies that expand the
basic communication range of–and consequently the service
offering to these nodes. In the case of mobile ad hoc grids, the
basic service provided by the nodes is the capability to allo-
cate computational resources to execute tasks. The expanded
range offered by MANETs permits that more nodes share
computational resources, but for this to be feasible special-
ized resource discovery and scheduling mechanisms are
needed. In the context of this paper, resource discovery
comprises gathering information about resources that mobile
nodes make available in the MANET, whereas resource
scheduling comprises selecting the most appropriate nodes
(from the point of view of resource provisioning) to execute
a particular set of tasks. We highlight that our focus in this
paper is on the resource discovery and the initial scheduling
of tasks to declared available resources. Hence, we do not
consider an eventual unavailability of a resource after it has
been discovered, selected, and is already running a submitted
task. Dealing with this particular issue is actually related to
techniques such as task migration24,39
, redundant submis-
sions for increased reliability30
, and so on. Such techniques
constitute another line of work on their own and are thus out
of scope of this paper.
In this paper, we propose the integration of resource
discovery and scheduling for mobile ad hoc grids into a single
protocol called DICHOTOMY (DIscovery and sCHeduling
prOTOcol for MobilitY). This protocol allows the computa-
tional tasks that comprise an application to be distributed
among the most resourceful nodes in a MANET. Such nodes
are selected automatically by the protocol, based on some
suitability criteria defined by the inquiring application. The
suitability of a node is determined in terms of the resources
the application is interested in and the relative importance
among them from the viewpoint of the application. By
always selecting the most resourceful nodes and making
advance reservations of the resources, our proposed protocol
provides an implicit scheduling mechanism that balances the
load among resource providers in the mobile ad hoc grid. For
computationally-intensive applications, such balance also
helps with lowering the average completion time of tasks in
the mobile ad hoc grid.
The DICHOTOMY protocol works in a peer-to-peer
fashion, regardless of underlying routing protocols. The
protocol can be classified as a purely query-based discovery
protocol–requests are broadcast over the network on demand
and providers reply to these requests accordingly. Query-
based protocols are known to cause waste of resources if
consumers naively broadcast requests by flooding (also
referred to as the broadcast storm problem37
) or if providers
naively reply to such requests (a.k.a. the reply implosion
problem11,8
). To mitigate broadcast storms, a simple mecha-
nism that limits the range of flooding is used. To avoid reply
implosions, an in-network filtering algorithm is employed,
which allows the more suitable replies to suppress unneces-
sary replies from other nodes alongside the paths used for
forwarding the more suitable replies back to the inquiring
node.
In our previous publications29,16,15
we gave an overview
of the architecture in which the DICHOTOMY protocol is
employed and of preliminary versions of the protocol and its
mechanisms. The present paper builds upon these, presenting
an extended version of the work that focuses specially on the
details of the protocol implementation and its performance
evaluation. In particular, besides providing further details
of the protocol implementation and design choices, we also
present a novel performance evaluation study that thor-
oughly analyzes the DICHOTOMY protocol covering key
aspects such as scheduling assessment, discovery efficiency
under mobility, and scalability analysis. Our prototypical
implementation–deployed both in an experimental ad hoc
grid testbed and in the NCTUns simulation and emulation
platform46
was focused on showing the feasibility of our
approach under operating conditions. We also devised a
simpler simulation model over the ns-2 simulator33
, to eval-
uate the scalability of our approach.
The remainder of the paper is structured as follows.
Section 2 provides some background on mobile ad hoc grids.
Section 3 introduces the DICHOTOMY protocol as well as
its main features and mechanisms. We present some relevant
implementation details in Section 4. We evaluate the perform-
ance of our proposed protocol in Section 5. Section 6 discusses
related work in discovery and scheduling in wireless and
mobile ad hoc grids. Finally, in Section 7 we summarize the
contributions of our proposed protocol and discuss possible
future work.
2. Background
In this section, we discuss why the discovery and sched-
uling mechanisms have to be different for MANETs and
present the basic ideas behind our proposed DICHOTOMY
protocol that impact discovery and scheduling procedures.
We also introduce the MoGrid architecture29
, our underlying
mobile ad hoc grid middleware.
2.1. Resource discovery and scheduling in mobile
ad hoc grids
To the best of our knowledge, the research on combined
resource discovery and scheduling for mobile ad hoc grids
is still rather preliminary. The mechanisms for resource
discovery and scheduling in such grids must be fundamen-
tally different from those used in wired grids as the former
are much more sensitive to network behavior than the latter.
This is due to the very dynamic nature of MANETs for
instance, nodes may move, or the QoS properties of the wire-
less medium can vary over short periods of time. In MANETs,
there are two ways for devices to exchange resource informa-
tion14
: queries and announcements. Queries involve some form
of devices sending requests throughout the network and
making the devices providing the required resource infor-
mation reply to these requests. Announcements permit that
3. 17Performance evaluation of a discovery and scheduling protocol for multihop ad hoc mobile grids2009; 15(4)
devices advertise their provided resources in the network
to interested devices. Most MANET applications actually
employ a combination of the two techniques. The scope of
diffusion of queries and announcements as well as the perio-
dicity and caching policies of announcements are important
parameters that determine the efficiency and accuracy of
resource discovery in such networks.
In the particular case of mobile ad hoc grids, announce-
ments are inadequate for offering resource information.
Besides the declaration of the availability of a resource
becoming time-sensitive due to node mobility, the availability
of highly dynamic resources, such as CPU load and available
memory, may vary considerably in very short periods of
time10,3
. Therefore, we adopt a purely query-based approach
in our proposed DICHOTOMY protocol (further details in
Section 3). Moreover, we argue that discovery and sched-
uling must be approached in an integrated way in mobile ad
hoc grids, in particular for multihop scenarios. This is due to
two main reasons:
1. The discovery of highly dynamic resources should
be associated with some form of advance reserva-
tion42,48
, so as to ensure that these resources are indeed
available at the resource provider when the resource
consumer submits the intended computational task.
2. The messaging overhead and the information required
for discovering available (and reachable) resource
providers in the mobile ad hoc grid can be used as
well for automatically selecting the set of most appro-
priate providers. The automatic selection of resource
providers bears resemblance to metascheduling
techniques in traditional grids7
, and is particularly
important for applications targeted at solving compu-
tationally-intensive problems.
As shown in Section 3, our proposed DICHOTOMY
protocol implements advance reservation and an in-network
filtering algorithm that allows the automatic selection of the
most suitable resource providers.
2.2. MoGrid architecture
To support the establishment of mobile ad hoc grids, we
proposed in Lima et al.29
a middleware architecture, called
MoGrid, which is depicted in Figure 1. In our work, we refer
to a mobile ad hoc grid as a set of (possibly heterogeneous)
mobile nodes in a MANET that manage resource usage
and provisioning for applications in a decentralized way.
Moreover, in our architecture resourceful nodes (e.g. laptops)
may provide resources to multiple application tasks simulta-
neously, while other, resource-constrained nodes (e.g. mobile
phones) may not provide resources at all in these cases, such
nodes may only ask for resources from remote nodes. We
further discuss the issue of node heterogeneity in Section 7.
In the remainder of this section we provide some
background on this architecture, so as to identify some
requirements on the design of the DICHOTOMY protocol.
The MoGrid architecture supports applications in two
phases. First, nodes acting as resource consumers discover
other nodes acting as resource providers by means of serv-
ices that the discovery layer offers. The DICHOTOMY
protocol is used for implementing these services. Second,
resource consumers submit application tasks to selected
resource providers according to the resources they make
available by means of services the submission layer offers.
Protocols within this layer are out of the scope of this paper;
nevertheless, we assume a resource usage model in which a
resource consumer has a group of independent tasks (e.g. bag
of tasks) which it needs to submit for execution on resource
providers. The adopted resource usage model implies the
use of a mechanism during the discovery phase that selects
multiple resource providers simultaneously. This is a major
shortcoming of current discovery approaches to MANETs, as
discussed in Section 6.
Each kind of application may have its specific resource
requirements on the mobile ad hoc grid. As an example, for
long-lived CPU-intensive applications battery power is more
important than highly available bandwidth when submit-
ting their tasks for execution, whereas storage capacity and
connection stability have greater importance to data replica-
tion applications. Therefore, the selection mechanism must
take into account the current level of resource usage asso-
ciated with a given provider and the relative importance
between its resources from the application’s point of view.
The MoGrid architecture supports applications imple-
mented directly on top of the discovery layer, or on top of an
application-specific layer (see Figure 1). One of the purposes
of the application-specific layers is to implement different
resource weightings according to different application types,
as for instance computationally-intensive, communication-
intensive, or data intensive applications (Section 5 provides
an example of implementation of an application-specific
layer).
The focus of the MoGrid architecture on resource
discovery instead of service discovery also implies the use of
a query-based approach to resource discovery, as opposed
to announcement-based approaches (see discussion on
Section 6). This is because the highly-variable availability
of resources such as CPU load and available memory may
demand a higher announcement rate, which in turn may
lead to an increased consumption of other resources in the
MANET, such as network bandwidth and energy.
Appl. Appl.
Appl. Appl. Appl. Appl.
Application-specific
layer
Application-specific
layer
Submission
layer
...
... ...
Discovery layer
(DICHOTOMY Protocol)
Figure 1. ModGrid arquitecture.
4. Journal of the Brazilian Computer Society18 Gomes ATA et al.
3. The DICHOTOMY Protocol
In this section, we present the DICHOTOMY protocol for
integrated discovery and scheduling in mobile ad hoc grids.
First, we discuss the basic operation of the proposed protocol
(Section 3.1). Next (Section 3.2), we describe the operation
of the adopted mechanism for determining the suitability
of nodes (acting as resource providers) to answer particular
requests from inquiring nodes (acting as resource consumers).
Finally (Section 3.3), we describe how the protocol avoids the
reply implosion problem.
3.1. Basic operation
The DICHOTOMY protocol defines two main messages:
INITIATORREQUEST (IREQ) and COLLABORATORREPLY
(CRep). An IReq message conveys:
i) A unique request identifier used to match requests to
replies (REQID);
ii) The maximum reply delay that the inquiring node
is willing to tolerate (MAXREPLYDELAY) c.f.
Section 3.2;
iii) Thenumberofresourceproviderstowhichtheinquiring
node wishes to submit tasks (NUMMAXREPLIES);
iv) Information about the resources the application is
interested in and the relative importance among them
we call this the contextual information (ctxtInfo) of the
request;
v) The current and maximum diameter (in number of
hops) of the request propagation (NUMHOPS and
maxHops, respectively); and
vi) A unique identification of the last node (e.g. its MAC
address) sending out the message (hopID). The CRep
message will be explained later in this section.
Figure 2 illustrates the basic operation and involved
message exchange within DICHOTOMY. An inquiring node
sends out IREQ messages to the other nodes in the mobile
ad hoc grid to ask them for resource provisioning. The IREQ
message is replicated at each intermediate node to form a
controlled flood limited by the maxHops parameter. This is
shown in Figure 2 as node i, the inquiring node, sends an
IREQ message to node t, an ordinary intermediate node, that
replicates the IREQ message to all its neighbors; the process
is repeated until the maxHops value is achieved, making the
IREQ message reach for instance nodes y and z.
Upon reception of an IREQ message, a node records it as
a pending request in a local data structure (pendingList). In
addition to REQID, numMaxReplies, and hopID, which are
obtained from the IREQ message, each entry of pendingList
has a numReplies field (initially set to 0) and two associated
timers (replyDelay and cleanUp). replyDelay is described
in Section 3.2; numReplies and cleanUp are described in
Section 3.3.
After updating PENDINGLIST, the receiver node replies
to an IREQ message depending on its willingness to collab-
orate as a resource provider, as described in Section 3.2. In
addition to replying to requests, nodes may also forward
requests to other nodes farther away from the inquiring node
in the mobile ad hoc grid, if numHops < maxHops. Such
forwarding is done through simple flooding to neighboring
nodes a scheme for inhibiting redundant rebroadcasts37
should be employed in this case. Before being forwarded,
a request has its numHops field incremented and its hopID
field updated with the identification of the current forwarding
node. Forwarding requests with updated hopIDs allows
nodes farther away from the inquiring node to keep track (in
their local pendingList structures) of the path traversed by
the request, which will be used for determining the return
path of the corresponding replies.
Nodes willing to collaborate as resource providers (here-
after, collaborating nodes) send CRep messages to inquiring
nodes in response to IREQ messages. In Figure 2, it is
assumed that all nodes in the mobile ad hoc grid collaborate
by replying to the inquiring node. In particular, nodes t, y,
and z send CRep messages as well as possibly other collab-
orating nodes whose CRep messages are represented by
dots in Figure 2. A CRep message informs the inquiring
node about the collaborating node address (identified by a
collAddr field) as well as its resource availability according
to the contextual information of interest indicated in the
Inquiring
Node
Collaboring Nodes
IReqhopID = i, numHops = 0
IReqhopID = t, numHops = 1
IReqhopID = ..., numHops = maxHops
IReqhopID = ..., numHops = maxHopsIReqhopID = t, numHops = 1
CReqcollAddr = z, retPath = i
CReqcollAddr = z, retPath = t
CReqcollAddr = y, retPath = t
CReqcollAddr = z, retPath = ...
CReqcollAddr = y, retPath = ...
CReqcollAddr = y, retPath = i
CReqcollAddr = t, retPath = i
i
...
...
...
...
t
z
y
Figure 2. Example of DICHOTOMY messages.
5. 19Performance evaluation of a discovery and scheduling protocol for multihop ad hoc mobile grids2009; 15(4)
corresponding request (resInfo field). Besides the collAddr
and resInfo fields, a CRep message also conveys:
i) The REQID matching that of the corresponding IREQ
message; and
ii) The identification of the node from which the corre-
sponding request was received (RETPATH)–the
replying node obtains such an identification from the
HOPID field in the corresponding IREQ message in
the PENDINGLIST.
A collaborating node sends a CRep message towards
the inquiring node through an application-level forwarding
mechanism that uses the already known path traversed by
the request. When a node receives a CRep message, it is proc-
essed according to Algorithm 1. If the reply corresponds to a
request the node has previously originated, the node proc-
esses the message and prevents this message to be further
forwarded in the network (lines 2 and 3). If the reply is instead
addressed to an inquiring node other than the receiver, the
latter first checks whether there is an entry for the corre-
sponding request in its pendingList structure (lines 6 and 7).
If not, the reply is silently discarded.I
Otherwise, the receiving
node determines whether this reply must be forwarded to the
inquiring node (line 8), according to the algorithm described
in Section 3.3. If this is the case, the node updates the reply’s
RETPATH field with the value of the hopID field stored in the
corresponding entry of pendingList and forwards the reply
(lines 9 and 10). This allows a neighbor node along the return
path to also forward such a reply to the inquiring node.
The application-level forwarding mechanism for reply
messages avoids the use of network-level routing protocols
that would generate additional network load on the MANET
during the discovery phase. Besides, with small modifications
I. If maxHops = ∞, this condition should not happen because every node in
the mobile ad hoc grid would in principle receive all IReq messages. Never-
theless, when a scheme for inhibiting redundant rebroadcasts is used, it is not
always guaranteed that an IReq message will reach all nodes in the network
even for maxHops = ∞.
in the hopID and retPath fields–instead of storing the last hop
in the path, they should in this case store the whole sequence
of traversed nodes, inquiring and collaborating nodes could
also learn the entire path between each other, and then use
source routing–a fairly common approach used in some
routing protocols for MANETs, such as DSR23
at the begin-
ning of the task submission phase. Details on the mapping
of the application-level forwarding mechanism for reply
messages onto the link level are discussed in Section 4.3.
3.2. Determining suitability
In the DICHOTOMY protocol, every node willing
to collaborate with the provision of a specific resource
delays the transmission of its CRep message according to
the REPLYDELAY timer in the corresponding entry of its
PENDINGLIST. Such a timer is set so that more resourceful
nodes reply earlier. This way, a node willing to collaborate
can detect, before sending its own CRep message, whether
other, more suitable nodes have already replied to the corre-
sponding request. If the total number of replies generated
in the mobile ad hoc grid is larger than the value NM
of the
numMaxReplies field in the corresponding IReq message,
and if the inquiring node chooses the NM
first received replies,
the protocol guarantees that the inquiring node discovers the
NM
most suitable nodes for providing the resource. Moreover,
when used together with the algorithm presented in Section
3.3, the strategy of delaying replies helps in reducing the total
number of replies being conveyed in the mobile ad hoc grid
by eliminating unnecessary additional replies alongside the
return path from the replying node to the inquiring one.
It should be remarked that the determination of reply
delays is flexible with regard to the resources to be taken into
account e.g. connectivity status, CPU load, available memory,
remaining battery power and the relative importance among
them. Information about resources to be considered when
computing the suitability of a node is conveyed by IREQ
messages in the CTXTINFO field. When a node receives a
request, it gathers its current state in terms of the resources of
interest to compute the reply delay. For this algorithm to work
correctly, all nodes in the mobile ad hoc grid must use the
same criterion for this computation. In our implementation
(c.f. Section 4), a collaborating node sets the REPLYDELAY
timer in the corresponding entry of its PENDINGLIST to
t units of time, as given by Equation 1:
t ω
α
= 1 2
=1 =1
−
−( )∑
∑i
N
i i
jj
N
P
P
D HSmax (1)
where 0 ≤ α ≤ 1 and 0 ≤ ω ≤ 1. N represents the number of
different resource types the collaborating node should take
into account. Pi
is the weight that describes the relative
importance of each resource type i from the viewpoint of the
application on the inquiring node, 1 ≤ i ≤ N. Both N and Pi
are
described as part of the ctxtInfo field in the request. Dmax
is the maximum reply delay, which is also obtained from the
Algorithm 1 CREP message main processing
Input: msg/*Received CREP*/
1: if FIRSTCOPY (msg) then
2: if MYREPLY (msg) then
3: PROCESS (msg)
4: return
5: end if
6: entry ← pendingList[msg.reqID]
7: if entry ≠ NULL then
8: if CANFORWARD (entry, msg) then
9: msg.retPath ← entry.hopID
10: FORWARD (entry.hopID, msg)
11: end if
12: return
13: end if
14: DISCARD (msg)
15: else
16: .../* Deal with duplicate replies */
17: end if
6. Journal of the Brazilian Computer Society20 Gomes ATA et al.
request (maxReplyDelay field). αi
is the normalized level of
current availability (in the interval [0,1]) of resource type i at
the collaborating node. ω indicates the willingness (also in the
interval [0,1]) of the collaborating node to participate in the
resource provisioning. t is undefined for ω = 0; such a value
means that no replies will be sent by the collaborating node
Section 4.1 provides an example of ω usage in our implemen-
tation. Finally, H and S are used for considering the transfer
delays that IREQ and CREP messages may experience. H is
the distance in hops between the collaborating node and the
inquiring node, and S is a tuning parameter representing the
mean transfer delay at each hop.
3.3. Avoiding the reply implosion problem
According to Algorithm 2, CREP messages are selectively
forwarded towards the inquiring node.
Whenever the function CANFORWARD() is called, it
increments the value NR
of the numReplies field in the entry
of pendingList corresponding to the received CREP message
(line 1), regardless of the receiving node being on the return path of
the reply. The node’s identification is then compared with the
value of the retPath field in the reply (line 2). If the values are
equal, it means the receiver is in the return path of the reply.
The receiving node, however, will only be able to forward
the reply to the inquiring node if NR
≤ NM
, where NM
is the
value of the numMaxReplies field in the corresponding entry
of its pendingList (line 3). If NR
> NM
, the node suppresses
the reply. Note that each intermediate node in the return
path implicitly informs its own vicinity due to the applica-
tion-level forwarding mechanism about requests that have
already been replied, thus allowing for further suppressions
at nodes nearby the reply’s return path.
To allow further suppressions, an entry in pendingList is
kept alive until its cleanUp timer expires. In our implementa-
tion, a node sets cleanUp for entries in pendingList connected
with replies not originated from this node to τmax
= Dmax
– 2HS
units of time. For entries associated with replies originated
from the node (i.e. its resource offerings), cleanUp is set to
2τmax
, to take account of advance reservations (c.f. Section 4.1).
Figure 3 illustrates an example of the operation of
Algorithm 2. In the initial configuration (Figure 3a), only
nodes w and z are within y’s transmission range. y receives
a reply to a request with reqID = 1000, and increments the
value NR
of the numReplies field in the corresponding entry
of its pendingList (Figure 3b). Since y is in the return path
of the reply (Figure 3c), y forwards such a message towards
w, which is y’s next hop in the return path. z overhears this
transmission due to the characteristics of the mapping of the
application-level forwarding mechanism onto the link level
one (discussed in Section 4.3) and then increments the value
NR
of the numReplies field in the corresponding entry of
its pendingList, but does not forward that reply because it
is not in the reply’s return path. z receives another reply to
the request with REQID = 1000 (Figure 3d), but although it
is in this reply’s return path, it does not forward the message
because the numMaxReplies field in the corresponding
entry of its pendingList indicates that it has already either
forwarded or overheard NM
messages.
4. Implementation
We have implemented the DICHOTOMY protocol in
Java, as part of the implementation of our MoGrid middle-
ware architecture29,II
The implementation is done in J2SE
according to the restrictions of the CDC (Connected Device
Configuration) profile of the Java ME. CDC is a stand-
ards-based framework for building and delivering mobile
applications that can be shared across a range of network-
connected personal mobile devices, such as grid services as
seen in mobile ad hoc grids discussed in this paper. Typically,
these devices include a 32-bit microprocessor/controller and
require about 2 MB of RAM and 2.5 MB of ROM for the Java
application environment. Our implementation of the protocol
uses a monitoring service available as part of the MoCA
architecture. This service is responsible for gathering infor-
mation about the current state of a mobile node, including
connectivity, CPU load, available energy and memory, and
disk storage space.
4.1. Setup of parameters
Parameters S and ω in Equation (1) are configurable in
our implementation. For our experiments (c.f. Section 5) we
set S = 10 ms which is of the same order of magnitude as
100 m one-trip packet delays for 1 Mbps transmission rate
and 1500-byte packets (disregarding delay variations due to
queuing and medium access contention). ω is computed as
ωusr/βL, where ωusr
describes the user’s level of interest (in
the interval [0,1]) in allowing its device to collaborate with
others on the mobile ad hoc grid, L is the number of entries
in a node’s pendingList corresponding to this node’s current
resource offerings, and β is an scalar factor. The denominator
βL implements a simple mechanism for advance reservation
by decreasing the node’s willingness to collaborate when the
number of pending requests at this node increases; β in this
case controls how fast the influence of a user’s willingness is
lowered as its pendingList grows. We set β = 2 arbitrarily in
our implementation. Finetuning this factor was left for future
work.
II The implementation is available for download at http://martin.lncc.br.
Algorithm 2 Function CANFORWARD ().
Input: entry/*Entry in PENDINGLIST */ and
msg/*Received CREP */
Output: boolean /* CREP is to be forwarded? */
1: entry.NR
← entry NR
+ 1
2: if msg.retPath = localID then
3: if entry.NR
≤ entry.NM
then
4: return true
5: end if
6: end if
7: return false
7. 21Performance evaluation of a discovery and scheduling protocol for multihop ad hoc mobile grids2009; 15(4)
4.2. Resource description and matching
In the implementation of the DICHOTOMY protocol, the
contextual information description conveyed by a request
message (CTXTINFO field) and the matching of such descrip-
tion to the resource availability on the collaborating nodes are
both based on simple attributes (key-value pairs). Semantic
description languages e.g. ontology languages32,34
could be
also employed. Such languages support queries with more
expressiveness and inference power, thereby allowing richer
matching options (e.g. partial matchings). Such expressive-
ness, however, incurs some additional computational cost in
terms of both processing time and memory footprint, which
may be undesirable in scenarios involving resource-poor
devices. The trade-off analysis of attribute and ontology-
based resource description and matching for mobile ad hoc
grids is out of the scope of this paper.
4.3. Application-level forwarding of reply messages
CRep messages are sent towards the inquiring node
through an application-level forwarding mechanism. There
are two alternative mappings of this scheme onto the link
level: using unicast or broadcast/multicast transmissions.
For link-level unicast mappings, the RETPATH value
associated with replies could be inferred from the destination
address field in the encapsulating packets (e.g. the destination
MAC address in IEEE 802.11 packets). This address field could
convey the value of the HOPID field in the corresponding
entry of PENDINGLIST which indicates the link-level
address of the next node in the return path–as part of func-
tion forward() (line 1 in Algorithm 1). By adopting such
mappings, the retPath field carrying the link-level address of
the next node in the return path could be omitted from the
CRep messages, and the statement msg.retPath←entry.hopID
(line 1) in Algorithm 1 could be removed. For a participating
node to overhear replies from its neighbors, however, its
network interface would have to work in promiscuous mode.
Besides the security issues involved, this alternative has the
drawback that, in promiscuous mode, the node must process
the payload of all packets (not only those pertaining to the
DICHOTOMY protocol) at the higher levels, which results
in a waste of resources (CPU, memory and energy) that are
crucial to computational tasks.
reqID NR
NM
hopID τ τmax
1000 3 4 x
...
reqID NR
NM
hopID τ τmax
1000 1 4 w
...
reqID NR
NM
hopID τ τmax
1000 4 4 x
...
reqID NR
NM
hopID τ τmax
1000 2 4 w
...
reqID NR
NM
hopID τ τmax
1000 3 4 x
...
reqID NR
NM
hopID τ τmax
1000 2 4 w
...
reqID NR
NM
hopID τ τmax
1000 4 4 x
...
reqID NR
NM
hopID τ τmax
1000 2 4 w
...
x
w
y
z
y’s pendingList
z’s pendingList z’s pendingList
y’s pendingList
z’s pendingList
y’s pendingList
supressed by z
NR
= NM
z’s pendingList
w
y
x
z
CRepreqID = 1000, retPath = w
CRepreqID = 1000, retPath = y
x
w z
y
x
w
y
z
(a) Initial configuration
(c) y rebroadcasts the reply towards w. (d) z receives another reply to the request
(b) y receives a reply to a request
Figure 3. Scenario illustrating the suppression of CREP messages by Algorithm 2.
8. Journal of the Brazilian Computer Society22 Gomes ATA et al.
For link-level broadcast/multicast mappings, nodes do
not need to set their network interfaces to work in promis-
cuous mode; however, the destination link address field in
packets encapsulating reply messages do not specify a single
recipient. Thus, the RETPATH field is necessary in such
messages and line 1 in Algorithm 1 must be kept. Even so, we
argue that the additional computational overhead of promis-
cuous mode operation introduced by unicast mappings can
do more harm for applications targeted at solving computa-
tionally-intensive problems than the additional transmission
overhead introduced by broadcast mappings. Therefore, we
have adopted link-level broadcast mappings for the applica-
tion-level forwarding mechanism in our implementation of
the DICHOTOMY protocol.
It is worth noting that for MANETs in which the media
access control is based on CSMA/CA (Carrier Sense Multiple
Acess/ Collision Avoidance), broadcast transmissions are
more unreliable and prone to collisions in comparison with
unicast transmissions37
. This is mainly due to the lack of
acknowledgments, of RTS/CTS (Request/Clear to Send)
dialogues, and of a mechanism for collision detection. The
problem of collisions in link-level broadcast transmissions
may be rather alleviated by the DICHOTOMY protocol, since
replies from different resource providers are time-shifted, as
discussed in Section 3.2. Regarding the lack of acknowledg-
ments, an implicit acknowledgment mechanism for broadcast
transmissions could be built upon the application-level
forwarding mechanism. To understand this, consider again
the example of Figure 3. When w receives the reply message
from y (Figure 3c), w will forward the message because it
is in the return path. Such a transmission will be overheard
by y (since it is within w’s range); y could then regard this
transmission as a higher-level acknowledgement from w.
Nonetheless, many subtle issues arise if a retransmission
policy based on such implicit acknowledgments is devised
to improve the reliability of the protocol. We argue that such
additionalcomplexityisnotworthwhile,sinceCRepmessages
are always subject to suppression along the remaining path
towards an inquiring node. Moreover, retransmissions add
delays that may render the retransmitted CRep message
useless at the inquiring node if it arrives after the predefined
maxReplyDelay. In fact, the experimental results presented
in Section 5.2 demonstrate that the DICHOTOMY protocol is
efficient even without such a retransmission policy.
5. Performance Evaluation
We carried out our experiments in testbed and simula-
tion environments, each of them to evaluate a different aspect
of the DICHOTOMY protocol. These are described in the
following subsections.
5.1. Scheduling Assessment
To assess the scheduling properties of the DICHOTOMY
protocol under an increasing volume of requests, we set up
an experimental ad hoc grid testbed. This testbed comprises 6
fixed, homogeneous nodes running Linux. These nodes have
beenarrangedinavarietyofmultihopscenarios,withonenode
in each of such scenarios being used as the resource consumer
and the remaining nodes as resource providers. Figure 4 illus-
trates the scenario from which the results presented in this
section have been obtained. Other scenarios provided similar
results, which have been omitted for brevity.
For our experiments, we implemented a simple master-
worker matrix-matrix multiplication application on top of
the testbed. To easily split the application into independent
tasks, we employed a very simple distributed multiplica-
tion algorithm: given matrices Am × n
and An × p
, a master node
computes Cm × p
= AB by selecting p worker nodes with the
DICHOTOMY protocol and sending to each worker node i
(1 ≤ i ≤ p) a copy of matrix A along with bn
i
×1 , i.e. the trans-
posed vector whose elements are those of the i-th column
of B. Each worker node i runs a task that computes matrix
c Abn
i
n
i
× ×1 1= and returns it to the master node, which then
builds the i-th column of C from cn
i
×1 . The selection of the
worker nodes in the experimental ad hoc grid that will run
the tasks is made by only considering those nodes with the
most available CPU and memory resources. We implemented
an application-specific layer for this purpose (c.f. Section 2.2),
with N = 2, PCPU
= 4, and Pmem
= 1 in Equation 1.
For each testbed scenario, we ran a total of 30 experi-
ments. In each experiment, the resource consumer sent a
total of 30 IREQ messages at regular intervals of 30 s and
set MAXREPLYDELAY = 10 s. Each resource provider s
selected by a specific IREQ message was sent a task to
compute cn
s
×1. Matrices Am×n
and Bn×p
were dimensioned in
such a way that such computation could generate a cumu-
lative load on the resource providers. Figure 5 shows the
cumulative load share for each node during one of these
experiments. The other experiments on the testbed scenario
depicted in Figure 4 provided similar results. We observe
in the figure that the slave nodes have their loads balanced
after the transient state (first 10 requests). This shows that our
protocol performed an efficient and dynamic load balancing
between resource providers under an increasing volume of
requests.
Provider
A
Provider
D
Provider
E
Provider
B
Provider
C
Consumer
Figure 4. Testbed scenario.
9. 23Performance evaluation of a discovery and scheduling protocol for multihop ad hoc mobile grids2009; 15(4)
We also used the testbed experiments described above
to analyze the scheduling quality that our protocol provides
to applications. We calculated the cumulative wall clock
time (the time difference between the start and finish of a
task) of all tasks generated in the testbed application after
the 30 experiments with our protocol. We then compared it
with the cumulative wall clock time achieved after 30 experi-
ments by a scheduler that selects worker nodes randomly. As
can be seen in Figure 6, our protocol schedules tasks among
worker nodes in such a way that the cumulative wall clock
time is approximately 36.5% smaller than that achieved by
a random scheduler. Further, the time overhead implied by
our protocol for discovery and scheduling, which is upper
bounded by the MAXREPLYDELAY parameter (10 s in our
simulation set up), is negligible with regard to the obtained
cumulative wall clock time of the tasks, which is in the order
of hundreds of thousands of seconds. These results indicate
that our protocol also has a positive impact on the applica-
tion efficiency.
5.2. Discovery efficiency under mobility
The simulation scenarios consisted of 40 nodes placed in an
obstacle-free, 500 × 500 m area. The initial position of each node
in a specific simulation was set randomly, with the constraints
that at the beginning of the simulation the nodes formed a
connected topology, and the distance among the nodes was
set to between 50 and 90% of the transmission range.
The first scenario consisted of a stationary topology. In
the remaining scenarios, the movement of nodes followed
the random walk model4
. In such a model, each node moves
in a random direction for some seconds–in a speed that is
uniformlydistributedintherange]0,Smax
]×thenchoosesanew
random direction, with no pauses in between such changes of
direction. Table 1 summarizes the parameters adopted in the
scenarios simulated with the NCTUns platform.
The discovery efficiency for each simulation scenario was
measured as a sample proportion calculated over 100 runs.
Each run consisted of a single resource consumer issuing
a single IReq message throughout the simulated MANET.
The sample proportion indicates the percentage of runs in
which the protocol delivered at least R replies from resource
providers to the resource consumer, as determined by the
NUMMAXREPLIES field in the IREQ message. The number
of collaborating nodes at each run was fixed at 10, which
corresponds to 25% of the nodes in the simulated scenarios.
Such a percentage was chosen based on the study by Hughes
et al.19
, which states that in Gnutella–a famous P2P, collabora-
tion-based file-sharing system–this percentage of participants
is responsible for 98% of all service provisions.
Figure 7 presents the discovery efficiency of the
DICHOTOMY protocol as a function of the maximum node
0
10
20
30
40
50
0 5 10 15 20 25 30
Loadshare(%)
Request number
A
B
C
D
E
Figure 5. Cumulative load of slave nodes.
0
50000
100000
150000
200000
DICHOTOMY RANDOM
Seconds
Figure 6. Cumulative wall clock time of tasks.
Table 1. Parameters for the NCTUns simulations.
Parameter Value
Number of nodes (N) 40
Number of resource providers 10
Maximum number of replies (R) 4
Transmission range 100 m
Maximum node speed (Smax
) 0 to 5 m/s
0
20
40
60
80
100
0 1 2 3 4 5
Discoveryefficiency(%)
Node speed (m/s)
Figure 7. Discovery efficiency in a mobile scenario.
10. Journal of the Brazilian Computer Society24 Gomes ATA et al.
speed (Smax
). The vertical error bars correspond to the 95%
confidence intervals for each sample proportion. The results
show that the protocol behaves well under situations of
human mobility (from 0.8 to 1.2 m/s, which corresponds to a
typical range for pedestrian walking speeds40
).
As can be observed in Figure 7, even for the stationary
scenario (Smax
= 0) the protocol does not reach 100% effi-
ciency–the sample proportion is 92%, with ±4.13 confidence
intervals. This is due to the drawbacks stated in Section 4.3
as regards the application-level forwarding mechanism for
reply messages being mapped onto link-level broadcast
transmissions in CSMA/CA enabled nodes.
5.3. Scalability Analysis
In principle, we could use our implementation of the
DICHOTOMY protocol on the NCTUns platform to evaluate
its scalability in scenarios with an increasing number of nodes.
Nevertheless, any simulation of the DICHOTOMY protocol
on the NCTUns platform was restricted to a maximum of
50 nodes; above these values the simulations generated a
load beyond the capacity of our NCTUns simulation infra-
structure. To allow a more extensive analysis of the scalability
of the DICHOTOMY protocol, we devised a simpler simu-
lation model over the ns-2 simulator33
. Our experiments in
such simulator considered fixed nodes forming topologies
with a constant number of nodes within the same transmis-
sion range (node density), so that the impact of increasing
the number of nodes in the ad hoc grid could be properly
evaluated. The results presented in this section correspond to
the average of 100 sample runs per simulated scenario with
a 95% confidence level. This analysis was mainly focused on
the evaluation of two metrics: the network load in the ad hoc
grid due to reply messages, and the suppression diameter of
these messages–the distance (in number of hops) between
the inquiring node and the nodes where these messages were
suppressed. Table 2 presents the parameters adopted in the
scenarios simulated by ns-2.
The average network load in the ad hoc grid due to
reply messages was computed using, for each scenario,
the mean number of packets involving these messages.
0
50
100
150
200
250
300
350
400
50 100 150 200
Numberoftransmissions
Number of nodes
Percentage of replying nodes (p) = 20%
0
100
200
300
400
500
600
700
800
20 40 60 80 100 120 140 160 180 200 220 240
Numberoftransmissions
Number of nodes
Percentage of replying nodes (p) = 40%
0
150
300
450
600
750
900
1050
1200
20 40 60 80 100 120 140 160 180 200 220 240
Numberoftransmissions
Number of nodes
Percentage of replying nodes (p) = 60%
0
200
400
600
800
1000
1200
1400
1600
20 40 60 80 100 120 140 160 180 200 220 240
Numberoftransmissions
Number of nodes
Percentage of replying nodes (p) = 80%
DICHOTOMY (R = 1)
DICHOTOMY (R = 2)
DICHOTOMY (R = 4)
DICHOTOMY (R = 6)
DICHOTOMY (R = 8)
DICHOTOMY (R = 10)
UCast
Figure 8. Network load in the mobile ad hoc grid due to reply messages.
11. 25Performance evaluation of a discovery and scheduling protocol for multihop ad hoc mobile grids2009; 15(4)
Importantly, this metric also allow us to imply whether there
is a significant reduction in energy consumption of devices
in a mobile ad hoc grid due to the suppression of replies,
given that transmissions are known to be responsible for a
high energy consumption. Using this metric, we compared
the DICHOTOMY protocol with a hypothetical query-
based discovery protocol in which service replies are sent
by unicast directly to inquiring nodes (we call it ``UCast’’)
in both protocols the inquiring nodes broadcast requests by
flooding, and no service announcements are employed. In our
belief, a comparison with advertisement- and hybrid-based
approaches would not make sense for mobile ad hoc grids
because the typical resources involved (e.g. CPU, memory)
are highly dynamic (c.f. Section 2).
Figure 8 presents the network load due to reply messages
as a function of the number of nodes for different percent-
ages of nodes willing to collaborate as resource providers.
The vertical error bars indicate the confidence intervals.
The results show that the adoption of the DICHOTOMY
protocol allows for an increasing reduction–with respect to
the ``UCast’’ protocol–in the total number of transmissions,
as the number of devices in the mobile ad hoc grid increases.
We also observe an even higher level of suppressions when
there is a larger percentage of nodes (p) in the mobile ad hoc
grid with interest in collaborating on resource provisioning.
These results suggest the scalability of our approach.
The suppression diameter of reply messages allow us to
evaluate the degree of distribution of the mitigation of the
forwarding burden provided by the DICHOTOMY protocol
among the nodes in a mobile ad hoc grid, and consequently
the distribution of energy savings among such nodes due to
the reduction in the amount of transmissions. Figures 9 and
10 present the distribution of suppressions as a cumulative
distribution function (CDF) for different numbers of nodes
and percentages of replying nodes. To better illustrate the
distribution of suppressions through the network, the results
presented in these figures are contrasted with a uniform CDF
(represented by the straight line in the figures).
Comparing all graphs in Figures 9 and 10, we observe a
better distribution of suppressions as the number of nodes
and the percentage of replying nodes (p) increase. Again, this
suggests the scalability of our proposed approach.
Comparing the curves of each individual graph, it is also
possible to verify that the distribution of the suppression
diameter becomes less uniform as the maximum number of
Table 2. Parameters for ns-2 simulations.
Parameter Value
Number of nodes (N) 10 to 240
Percentage of resource providers (p) 20% to 80%
Maximum number of replies (R) 1 to 10
Node density 5
Transmission range 12.5 m
Distance between nodes 10 m
replies (R) increases, with a tendency to suppressions being
concentrated closer to the inquiring node. This is an expected
behavior, since less suppressions occur at nodes farther away
from the inquiring node and replies follow convergent paths
towards such node.
6. Related Work
In spite of some research efforts over the past few years
on wireless and mobile ad hoc grids, none of it as far as we
can see has addressed the issues related to the interplay
of resource discovery and scheduling in such grids. In the
following we survey relevant research related to these two
areas.
6.1. Resource discovery
Although some papers point out the need for resource
discovery protocols in wireless grids31,35
, no work has explic-
itly addressed this area for multihop mobile ad hoc grids.
A close subject–service discovery protocols (SDPs)–has
been a hot topic in the area of MANET research44
and could
arguably be extended or adapted for resource discovery
purposes. Nonetheless, most of the SDPs for MANETs are
based on announcements, allowing nodes to advertise serv-
ices in the network; nodes interested in such services cache
the related advertisements. Clearly, such protocols are inad-
equate for offering computational services that depend on
highly dynamic resources, such as CPU load and available
memory. The availability of such resources may vary consid-
erably in short periods of time10,3
, thus demanding frequent
announcements, which in turn may lead to an increased
consumption of other resources in the MANET, such as
network bandwidth and energy. In this context, some pieces
of work propose improvements to the broadcasting of service
requests in multihop MANETs, so as to reduce the amount
of packet transmissions related to such requests. Examples
include Konark27
, Group-based Service Discovery (GSD)5
,
and Field Theoretic Approach (FTA)28
.
Konark introduces the concept of service gossiping, in
which a node can selectively forward both service requests
and replies based on cached announcements from other
nodes. The efficiency of the Konark approach, however, is
highly dependent on caching of service information, thus
being inadequate for grid-like computational services. The
GSD architecture controls request broadcasts based on the
semantic grouping of services as ontology classes, but its effi-
ciency is also dependent on the advertisement and caching
of such classes. When compared with the two previous
approaches, FTA further reduces the amount of transmis-
sions related to request forwarding by adopting an analogy
of electrostatic fields. In the FTA approach, an inquiring node
sends out a service request (a negative test charge), which
is ``attracted’’ by the most appropriate service instance (the
positive charge that creates the field with highest potential).
This way, FTA allows the automatic selection of a single node
as the most suitable provider of a particular service, with
12. Journal of the Brazilian Computer Society26 Gomes ATA et al.
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 1 2 3 4 5 6 7
SuppressionCDF
Suppression diameter
Number of nodes = 60
Percentage of replying nodes (p) = 60%
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 1 2 3 4 5 6 7 8 9 10
SuppressionCDF
Suppression diameter
Number of nodes = 120
Percentage of replying nodes (p) = 60%
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
SuppressionCDF
Suppression diameter
Number of nodes = 240
Percentage of replying nodes (p) = 60%
Uniform CDF
DICHOTOMY (R = 1)
DICHOTOMY (R = 2)
DICHOTOMY (R = 4)
DICHOTOMY (R = 6)
DICHOTOMY (R = 8)
DICHOTOMY (R = 10)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 1 2 3 4 5 6 7 8 9 10
SuppressionCDF
Suppression diameter
Number of nodes = 120
Percentage of replying nodes (p) = 20%
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
SuppressionCDF
Suppression diameter
Number of nodes = 240
Percentage of replying nodes (p) = 20%
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 1 2 3 4 5 6 7
SuppressionCDF
Suppression diameter
Number of nodes = 60
Percentage of replying nodes (p) = 20%
Uniform CDF
DICHOTOMY (R = 1)
DICHOTOMY (R = 2)
DICHOTOMY (R = 4)
DICHOTOMY (R = 6)
DICHOTOMY (R = 8)
DICHOTOMY (R = 10)
Figure 10. Distribution of reply suppressions (60% of replying nodes
in the mobile ad hoc grid).
Figure 9. Distribution of reply suppressions (20% of replying nodes
in the mobile ad hoc grid).
13. 27Performance evaluation of a discovery and scheduling protocol for multihop ad hoc mobile grids2009; 15(4)
smaller overhead on the MANET as compared with Konark
and GSD. Nevertheless, this approach disregards the auto-
matic selection of multiple providers, and its efficiency is also
highly dependent on the spread of potentials, which is based
on periodic announcements.
Other researchers have focused on extending routing
protocols to accomodate service discovery. One example
comes from Varshavsky et al.43
and their cross-layer approach
to integrating service discovery functionality within the
DSR22
(query-based) and DSDV38
(announcement-based)
routing protocols. This approach and others similar to it26,6
is also inappropriate for mobile ad hoc grids, since either
its discovery efficiency is again dependent on caching of
announced service information, or all replies from service
providers matching the service description of a client’s query
arrive at the inquiring node for local selection by the client,
thus wasting communication and energy resources.
6.2. Resource Scheduling
As far as traditional grids are concerned, many different
scheduling strategies have been developed along the
years1,12,47
. Only very recently, however, have specific sched-
uling strategies for wireless and mobile ad hoc grids emerged
in the literature17,25,30,20,49
. Most of them employ task replication
to optimize some objective function related to the inherent
limitations in processing, memory, battery power, and wire-
less communications capabilities of mobile devices.
Huang et al.17
propose a two-level scheduling model
suitable for wireless grids. The first level of their model is
responsible for mapping tasks to fixed grid nodes; some of
these nodes act as proxies between a wireless domain (e.g.
an area covered by an access point) and the fixed grid. The
second level conducts scheduling within each proxy-centric
wireless domain. The proxy runs a revised Min-Min heuristic
algorithm, which aims at minimizing energy consumption at
the mobile nodes. A similar approach based on hierarchical
scheduling is proposed by Katzaros and Polyzos25
, with the
difference that task replication is employed to treat discon-
nection events. Both approaches are inadequate for mobile
ad hoc grids due to the need for a fixed node acting as the
scheduler.
Litke et al.30
focus on shortening the overall system
response time with a scheme for task replication based on
the knapsack problem formulation. Their strategy aims
at maximizing the utilization of computational resources
provided by the mobile nodes. A probability function is
used for computing the availability of each node based on
its current failure rate (e.g. number of times it was unreach-
able in the network), so that a node only receives tasks that
may be completed before its mean time to failure (MTTF).
Nevertheless, Litke et al. disregard energy consumption,
which–in the case of multihop mobile ad hoc grids–may limit
the operational life time of the whole system.
Zong et al.49
aim at reducing schedule lengths of prece-
dence-constrained parallel tasks while conserving energy at
the mobile nodes. Their strategy relies on judiciously repli-
cating tasks so that energy consumption related to inter-task
communication is diminished; however, the process of node
selection, as described in Wolf et al.49
, implies a centralized
discovery service.
Hummel and Jelleschitz20
propose a decentralized sched-
uler, thus bearing more resemblance to our approach; each
mobile node decides autonomously whether to process a
submitted task depending on its current and estimated near
future capabilities. Their main focus, however, is on providing
fault tolerance through task replication, which is coordinated
by means of task queues managed in a distributed virtual
shared memory. Crucially, their solution does not take into
account the waste of communication and energy resources
due to this coordination.
7. Summary and Outlook
In this paper, we have presented the specification, imple-
mentation, and performance evaluation of a novel protocol
(DICHOTOMY) for integrated resource discovery and
scheduling on multihop mobile ad hoc grids. Overall, our
experimental results show that:
• Our protocol does appropriate resource scheduling,
allowing an efficient load balancing among resource
providers and having a positive impact on the appli-
cation efficiency under an increasing volume of
discovery requests;
• The discovery efficiency–i.e. the percentage of success-
fully answered requests–is kept at acceptable levels in
the mobile application scenarios we are interested in,
which involves pedestrian (walking) mobility;
• The proposed protocol scales very well with respect
to an increasing number of nodes in comparison
with the traditional query-based solutions for service
discovery, since it increases the total amount of energy
savings due to packet transmissions;
• Thesuppressionofrepliesperformedbyourin-network
filtering algorithm is not concentrated at specific points
of a MANET–instead, the filtering is distributed among
the nodes. As a consequence of the distributed reduc-
tion in the amount of transmissions, the energy savings
due to nodes having fewer replies to retransmit are also
distributed throughout the network.
During the development of this work, some aspects have
been identified for future investigation:
• A more elaborated mechanism for advance reserva
tions may be devised, including the treatment of
resource ``underbookings’’ a situation that might
happen if the collaborating node reserves resources
that are not actually used because its reply is
suppressed before arriving at the inquiring node.
Although such a reservation is temporary (as defined
by the CLEANUP timer), it may affect concurrent
requests.
• The MAXREPLYDELAY parameter has an impor-
tant impact on the efficiency of the DICHOTOMY
protocol. Finetuning this parameter e.g. as a func-
14. Journal of the Brazilian Computer Society28 Gomes ATA et al.
tion of the transmission delay of messages is essential
to increase the discovery efficiency under mobility
(since messages typically take no more than a few
hundred milliseconds for delivery), and also to reduce
the discovery time without increasing the number of
reply collisions (which is achieved through the asyn-
chronism in the transmission of these messages).
• The investigation of heterogeneity-aware suitability
criteria is an interesting open issue. In this context,
the theoretical and simulation study by Huang et al.18
has recently brought interesting insights into how
to handle nodes with heterogeneous computational
power.
• Finally, in our current implementation the suitability
of a resource provider is only computed by its own
context (i.e. the state of its own resources) and not
the context of intermediate nodes in its path to the
inquiring node. This did not affect our results in the
testbed because it formed topologies with just few
hops. We are currently evaluating to what extent
disregarding the context of intermediate nodes may
affect a mobile ad hoc grid and investigating alterna-
tive solutions.
Acknowledgements
This work has been partially funded by the Brazilian
Ministry of Science and Tecnology (MCT), CNPq, and
FAPERJ.
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