The document summarizes recent developments in node clustering techniques for wireless sensor networks. It discusses how clustering helps organize sensor networks into hierarchies to balance load and prolong network lifetime. Several key clustering approaches are described and classified based on their objectives, design principles, and assumptions. Distributed clustering is preferred over centralized approaches for large-scale sensor network deployments. Representative clustering protocols like LEACH and HEED are compared in terms of their design, criteria for electing cluster heads, assumptions, and overhead. Challenges in practical deployment of clustering techniques are also highlighted.
The document proposes an improved data routing protocol for wireless sensor networks. It aims to address deficiencies in existing chain-based routing protocols like Chiron and PEGASIS that can cause longer transmission delays and redundant paths. The key aspects of the proposed protocol are:
1) The sensing area is divided into fan-shaped groups using beamforming from the base station, instead of concentric clusters. Shorter chains are formed within each group for data transmission.
2) The node with maximum residual energy in each chain is elected as the chain leader, rather than taking turns, to aggregate and transmit data to the base station.
3) Transmission between chain leaders is optimized to avoid longer distances and redundant paths.
Spread Spectrum Based Energy Efficient Wireless Sensor NetworksIDES Editor
The Wireless Sensor Networks (WSN) is
considered to be one of the most promising emerging
technologies. However one of the main constraints which
is holding back its wide range of applications is the
battery life of the sensor node and thus effecting the
network life. A new approach to this problem has been
presented in this paper. The proposed method is suitable
for event driven applications where the event occurrence
is very rare. The system uses spread spectrum as a means
of communication.
Simulation Based Routing Protocols Evaluation for IEEE 802.15.4 enabled Wirel...IDES Editor
Wireless sensor network (WSN) is emerging as a
major research field in computer networks over the last decade
due to its wide variety of embedded real time applications.
Sensor networks have infrastructure-less architecture because
of frequently varying topology and link status. Routing is an
extremely challenging task for battery-powered resourceconstrained
WSN, since it is main cause for energy depletion
and energy must be utilized prudently to enhance lifetime
for sensor networks. This drives a myriad of research efforts
aiming at efficient data dissemination. In this paper we
analyze how efficiently MANET specific routing protocols
OLSR (Optimized Link-State Routing protocol), DYMO
(Dynamic MANET On-demand) and ZRP (Zone Routing
Protocol) perform in IEEE 802.15.4 enabled wireless sensor
networks and evaluate their simulation results using Qualnet
simulator. Several simulations were carried out under varying
network size and offered load for performance evaluation and
relative comparison of protocols is reported in terms of average
end to end delay, throughput and jitter.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
BOTTLENECK DETECTION ALGORITHM TO ENHANCE LIFETIME OF WSNijngnjournal
The document proposes a bottleneck detection algorithm to identify weak areas in a wireless sensor network and enhance the network lifetime. It detects bottleneck and minimal bottleneck zones where sensor nodes deplete their energy quickly. The algorithm identifies these weak zones and two additional sensor node deployment strategies are proposed - random deployment that places extra nodes everywhere and targeted deployment that places nodes in identified bottleneck areas. Simulations show the deployment strategies increase network lifetime parameters like throughput and packet delivery compared to the existing system. The bottleneck detection algorithm and additional node placements help balance energy usage and form stable links to prolong the wireless sensor network lifetime.
Cluster-based Target Tracking and Recovery Algorithm in Wireless Sensor NetworkIJASCSE
This document summarizes a research paper that proposes an energy efficient recovery technique for target tracking in wireless sensor networks. It begins with an introduction to target tracking in WSNs and the related challenges of energy efficiency and recovery when targets are lost. It then reviews existing target tracking and recovery techniques. The proposed technique uses dynamic clustering to predict target locations and only wakes clusters near the predicted path to save energy. The recovery mechanism has three steps: 1) the current cluster head announces a lost target, 2) it initiates recovery by waking nearby clusters to search predicted locations, and 3) once the target is found, only tracking clusters remain active while others sleep. The paper argues this approach reduces communication overhead and active clusters compared to existing
The document discusses clustering algorithms for wireless sensor networks. It describes four categories of clustering algorithms: 1) identity-based, which select cluster heads based on node identifiers, 2) neighborhood-based, which select heads based on number of neighbors, 3) probabilistic, which assign selection probabilities, and 4) biologically-inspired. Example algorithms described include the Linked Cluster Algorithm, Highest Connectivity Algorithm, and Weighted Clustering Algorithm. Clustering helps optimize energy usage and extend network lifetime by reducing transmissions and aggregating data at cluster heads.
EFFICIENT HIERARCHICAL ROUTING PROTOCOL IN SENSOR NETWORKSijassn
Wireless sensor network (WSN) is the network of hundreds and thousands of micro-sensor nodes,
connecting each other by a wireless medium.WSN provide reliable sensing of the environment, detecting
and reporting events to the sink. One of the most important constraints of WSN is energy consumption.
Since the micro sensors are small in dimension, batteries are necessary to produce power to the network. In
this paper, we have proposed an algorithm for hierarchy based protocols of wireless sensor networks,
which consist of two groups of sensor nodes in a single cluster node. Each cluster consists of a three cluster
head. The event driven data sensing mechanism is used in this paper and this sensed data is transmitted to
the master section head. The gathered data is transmitted to the sink via mobile agent. Hence efficient way
of data transmission is possible with larger group of nodes. In this approach of using hierarchy based
protocols; the lifetime of the sensor network is increased. This paper proposes an innovative approach of
cluster head election. The results are compared with LEACH protocol and proved to be energy efficient.
The document proposes an improved data routing protocol for wireless sensor networks. It aims to address deficiencies in existing chain-based routing protocols like Chiron and PEGASIS that can cause longer transmission delays and redundant paths. The key aspects of the proposed protocol are:
1) The sensing area is divided into fan-shaped groups using beamforming from the base station, instead of concentric clusters. Shorter chains are formed within each group for data transmission.
2) The node with maximum residual energy in each chain is elected as the chain leader, rather than taking turns, to aggregate and transmit data to the base station.
3) Transmission between chain leaders is optimized to avoid longer distances and redundant paths.
Spread Spectrum Based Energy Efficient Wireless Sensor NetworksIDES Editor
The Wireless Sensor Networks (WSN) is
considered to be one of the most promising emerging
technologies. However one of the main constraints which
is holding back its wide range of applications is the
battery life of the sensor node and thus effecting the
network life. A new approach to this problem has been
presented in this paper. The proposed method is suitable
for event driven applications where the event occurrence
is very rare. The system uses spread spectrum as a means
of communication.
Simulation Based Routing Protocols Evaluation for IEEE 802.15.4 enabled Wirel...IDES Editor
Wireless sensor network (WSN) is emerging as a
major research field in computer networks over the last decade
due to its wide variety of embedded real time applications.
Sensor networks have infrastructure-less architecture because
of frequently varying topology and link status. Routing is an
extremely challenging task for battery-powered resourceconstrained
WSN, since it is main cause for energy depletion
and energy must be utilized prudently to enhance lifetime
for sensor networks. This drives a myriad of research efforts
aiming at efficient data dissemination. In this paper we
analyze how efficiently MANET specific routing protocols
OLSR (Optimized Link-State Routing protocol), DYMO
(Dynamic MANET On-demand) and ZRP (Zone Routing
Protocol) perform in IEEE 802.15.4 enabled wireless sensor
networks and evaluate their simulation results using Qualnet
simulator. Several simulations were carried out under varying
network size and offered load for performance evaluation and
relative comparison of protocols is reported in terms of average
end to end delay, throughput and jitter.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
BOTTLENECK DETECTION ALGORITHM TO ENHANCE LIFETIME OF WSNijngnjournal
The document proposes a bottleneck detection algorithm to identify weak areas in a wireless sensor network and enhance the network lifetime. It detects bottleneck and minimal bottleneck zones where sensor nodes deplete their energy quickly. The algorithm identifies these weak zones and two additional sensor node deployment strategies are proposed - random deployment that places extra nodes everywhere and targeted deployment that places nodes in identified bottleneck areas. Simulations show the deployment strategies increase network lifetime parameters like throughput and packet delivery compared to the existing system. The bottleneck detection algorithm and additional node placements help balance energy usage and form stable links to prolong the wireless sensor network lifetime.
Cluster-based Target Tracking and Recovery Algorithm in Wireless Sensor NetworkIJASCSE
This document summarizes a research paper that proposes an energy efficient recovery technique for target tracking in wireless sensor networks. It begins with an introduction to target tracking in WSNs and the related challenges of energy efficiency and recovery when targets are lost. It then reviews existing target tracking and recovery techniques. The proposed technique uses dynamic clustering to predict target locations and only wakes clusters near the predicted path to save energy. The recovery mechanism has three steps: 1) the current cluster head announces a lost target, 2) it initiates recovery by waking nearby clusters to search predicted locations, and 3) once the target is found, only tracking clusters remain active while others sleep. The paper argues this approach reduces communication overhead and active clusters compared to existing
The document discusses clustering algorithms for wireless sensor networks. It describes four categories of clustering algorithms: 1) identity-based, which select cluster heads based on node identifiers, 2) neighborhood-based, which select heads based on number of neighbors, 3) probabilistic, which assign selection probabilities, and 4) biologically-inspired. Example algorithms described include the Linked Cluster Algorithm, Highest Connectivity Algorithm, and Weighted Clustering Algorithm. Clustering helps optimize energy usage and extend network lifetime by reducing transmissions and aggregating data at cluster heads.
EFFICIENT HIERARCHICAL ROUTING PROTOCOL IN SENSOR NETWORKSijassn
Wireless sensor network (WSN) is the network of hundreds and thousands of micro-sensor nodes,
connecting each other by a wireless medium.WSN provide reliable sensing of the environment, detecting
and reporting events to the sink. One of the most important constraints of WSN is energy consumption.
Since the micro sensors are small in dimension, batteries are necessary to produce power to the network. In
this paper, we have proposed an algorithm for hierarchy based protocols of wireless sensor networks,
which consist of two groups of sensor nodes in a single cluster node. Each cluster consists of a three cluster
head. The event driven data sensing mechanism is used in this paper and this sensed data is transmitted to
the master section head. The gathered data is transmitted to the sink via mobile agent. Hence efficient way
of data transmission is possible with larger group of nodes. In this approach of using hierarchy based
protocols; the lifetime of the sensor network is increased. This paper proposes an innovative approach of
cluster head election. The results are compared with LEACH protocol and proved to be energy efficient.
Engineering Research Publication
Best International Journals, High Impact Journals,
International Journal of Engineering & Technical Research
ISSN : 2321-0869 (O) 2454-4698 (P)
www.erpublication.org
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.
Clustering effects on wireless mobile ad hoc networks performancesijcsit
A new era is dawning for wireless mobile ad hoc networks where communication will be done using a
group of mobile devices called cluster, hence clustered network. In a clustered network, protocols used by
these mobile devices are different from those used in a wired network; which helps to save computation
time and resources efficiently. This paper focuses on Cluster-Based Routing Protocol and Dynamic Source
Routing. The results presented in this paper illustrates the implementation of Ad-hoc On-Demand Distance
Vector routing protocol for enhancing mobile nodes performance and lifetime in a clustered network and to
demonstrate how this routing protocol results in time efficient and resource saving in wireless mobile ad
hoc networks.
1) The document proposes choosing autonomous nodes strategically to improve the robustness of coupled networks against cascading failures.
2) It shows that by selecting the 10% of nodes with highest betweenness centrality as autonomous, the robustness is significantly improved compared to random selection. This changes the percolation transition from discontinuous to continuous.
3) Even for networks with narrow degree distributions like Erdos-Renyi graphs, proper selection of autonomous nodes based on betweenness leads to large robustness gains compared to random selection.
Joint Interference Coordination and Spatial Resource ReuseIJMTST Journal
Multihop cellular networks (MCNs) have drawn tremendous attention due to its high throughput and extensive coverage. Deploying relay nodes is foreseen a cost-efficient solution to combat the severe propagation loss at cell edge. However, relay cell coverage is limited by the low transmit power, limited antenna capabilities and wireless backhaul link bottleneck which may lead to load imbalances and hence low resource utilization efficiency. Further challenges in relay deployments are attributed to increased interference levels in the network compared with macro cell-only deployments, causing degradation of the user throughput. In this context, relay cell coverage expansion and interference coordination techniques are expected to improve the performance of relay deployments. In this study, we analyze the impact of the additional interference due to the relay node transmissions. Jointly with our previous study on cell expansion, spatial resource reuse from the graph-theoretical perspective. Next, our focus shifts to developing a simple but efficient radio resource management algorithm which enables the spatial resource reuse, the pricing- based radio resource management (PRRM) strategy. The PRRM performs spatial reuse for interference-free users operating in the high signal-to-interference-and-noise ratio (SINR) region, while guaranteeing the signal quality of interference-susceptible users usually located near the coverage boundary. By applying the PRRM, we evaluate the potential benefits of the spatial resource reuse.
GPS-less Localization Protocol for Underwater Acoustic NetworksCSCJournals
The problem of underwater positioning is increasingly crucial due to the emerging importance of sub-sea activities. Knowledge of node location is essential for many applications for which sensor networks can be used. At the surface, positioning problems have been resolved by the extended use of GPS, which is straightforward and effective. Unfortunately, using GPS in the sub-sea environment is impossible and positioning requires the use of special systems. One of the major challenges in the underwater acoustic networks (UANs) area of research is the development of a networking protocol that can cope with the management of a dynamic sub-sea network. We propose a scheme to perform node discovery, using only one seed node (primary seed) in a known position. The discovery protocol can be divided into two parts: First, building up the relative co-ordinate system. Second, involving more remote nodes becoming seed nodes for further discoveries. Four different algorithms have been investigated; (i) Farthest/Farthest Algorithm, (ii) Farthest/Nearest Algorithm, (iii) Nearest/Farthest Algorithm and (iv) Nearest/Nearest Algorithm. We investigated the performances of random and fixed (grid) network topologies. Different locations of primary seed node were exercised and statistics for node discovery will be reported.
Characterization of directed diffusion protocol in wireless sensor networkijwmn
Wireless sensor network (WSN) has enormous applications in many places for monitoring the environments
of importance. Sensor nodes are capable of sensing, computing, and communicating. These sensor nodes
are energy constraint and operated by batteries. Since energy consumption is an important issue of WSN,
there have been many energy-efficient protocols proposed for the WSN. Directed diffusion (DD) is a datacentric
protocol that focuses on the energy efficiency of the networks. Since the first proposal of DD
protocol by Deborah, there have been various versions of DD protocols proposed by many scientists across
the globe. These upgraded versions of DD protocols add on various features to the original DD protocol
such as energy, scalability, network lifetime, security, reliability, and mobility. In this paper, we discuss
and classify various characteristics of themost populardirected diffusion protocols that have been proposed
over couple of years.
DEVELOPMENT OF SOM NEURAL NETWORK BASED ENERGY EFFICIENT CLUSTERING HIERARCHI...ijassn
The document summarizes a research paper that proposes a new clustering protocol called SOM-PEG for wireless sensor networks. SOM-PEG is based on the PEGASIS protocol but uses self-organizing map (SOM) neural networks to select cluster heads, with the goal of improving network lifetime and reducing energy consumption compared to PEGASIS. The document provides background on PEGASIS and SOM neural networks, describes the SOM-PEG algorithm and simulation setup, and discusses performance metrics for evaluating and comparing routing protocols in wireless sensor networks.
This document summarizes and compares various routing protocols for wireless sensor networks. It categorizes routing protocols into three types: data-centric, hierarchical, and location-based. For each type, it describes some representative protocols, outlines their advantages and disadvantages, and discusses their application domains. The document concludes that routing in wireless sensor networks faces challenges due to constraints like limited energy, bandwidth and memory in sensor nodes, and more research is still needed to develop efficient and adaptive routing techniques.
Current issue- International Journal of Advanced Smart Sensor Network Systems...ijassn
With the availability of low cost, short range sensor technology along with advances in wireless networking, sensor networks has become a hot topic of discussion. The International Journal of Advanced Smart Sensor Network Systems is an open access peer-reviewed journal which focuses on applied research and applications of sensor networks. While sensor networks provide ample opportunities to provide various services, its effective deployment in large scale is still challenging due to various factors. This journal provides a forum that impacts the development of high performance computing solutions to problems arising due to the complexities of sensor network systems. It also acts as a path to exchange novel ideas about impacts of sensor networks research.
The Wireless Sensor Network is one of the most significant purposes behind the accomplishment of long range wireless communication. Frequent connectivity failures are occurred in the sensor-organised network due to obstruction, snags, message drop because of node energy depletion; obstacle and so forth. The total communication gets collapsed if there any lessening in the nature of correspondence or quality between the sensor nodes or from the sensor nodes to the sink nodes and this prompts to connection failures. To overcome the frequent connectivity failures we propose Diminishing Connectivity Failures by Auto-Reconfiguration in WSN (DCFA). This scheme provides steadfast routes to reduce the connectivity failure and improve the network performance.
This document summarizes a research paper presented at the National Conference on Current Trends in Computer Science and Engineering. The paper proposes a Sink-initiated Geographic Multicast (SIGM) protocol for wireless sensor networks that allows mobile sinks to construct their own data delivery paths from a source node and merge these paths to form a multicast tree. This reduces location updates and achieves fast multicast tree construction and data delivery. The paper also presents a round-based virtual infrastructure to further improve the SIGM protocol's energy efficiency and ability to handle sink mobility. Simulation results show SIGM outperforms other source-initiated multicast protocols in terms of energy consumption and data delivery latency.
Data Centric Approach Based Protocol using Evolutionary Approach in WSNijsrd.com
The evolution of wireless communication and circuit technology has enabled the development of an infrastructure consists of sensing, computation and communication units that makes administrator capable to observe and react to a phenomena in a particular environment. In a Wireless Sensor Network (WSN), nodes are scattered densely in a large area. Sensor nodes can communicate with the sink node directly or through other nodes. Data transmission is the major issue in WSN. Each node has limited energy which is used in transmitting and receiving the data. Various routing protocols have been proposed to save the energy during the transmission of data. data centric approach based routing protocol which efficiently propagates information between sensor nodes in an energy constrained mode. This paper proposes a data centric routing Using evolutionary apporoach in WSN.The main objective of this protocol with evolutionary apporoach is to use artificial intelligence, to reduce the energy consumption by the nodes in transmitting and receiving the data. Implementation of Basic SEP, intelligence cluster routing and proposed protocols will be done using MATLAB.
Routing protocol on wireless sensor networkshashankcsnits
The document summarizes routing protocols for wireless sensor networks. It first defines wireless sensor networks and describes their key characteristics. It then surveys traditional routing techniques like flooding and gossiping, as well as current techniques including flat routing protocols like SPIN and directed diffusion, hierarchical routing protocols like LEACH and PEGASIS, and location-based routing protocols like GEAR. For each protocol, it provides a brief overview of how it works and compares their advantages and disadvantages. In conclusion, it states that hierarchical routing protocols generally outperform flat routing protocols, and references several papers on sensor network routing.
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.
CUTTING DOWN ENERGY USAGE IN WIRELESS SENSOR NETWORKS USING DUTY CYCLE TECHNI...ijwmn
The document summarizes an algorithm proposed to reduce energy consumption in wireless sensor networks using duty cycling and multi-hop routing. The key aspects of the algorithm are:
1) Layering the network environment based on size and identifying the optimal number of cluster heads in each layer.
2) Selecting the first layer closest to the sink as the "gateway layer" and stopping energy usage in half of these sensors to extend the network lifespan.
3) Using multi-hop routing whereby cluster heads send data to heads in the above layer until the gateway layer, which then sends to the static or mobile sink.
4) Simulation results showed the proposed algorithm performs better than LEACH and ELEACH in terms of
This document summarizes and compares the quality of service (QoS) metrics of the DSR, AODV, and RPAR routing protocols in wireless multimedia sensor networks. It discusses the hexagonal deployment of sensor nodes and evaluates the protocols based on QoS parameters like throughput, delay, dropped data ratio, network load, and retransmission attempts. The document finds that the hexagonal grid deployment and RPAR framework provide better performance compared to DSR and AODV in terms of energy efficiency and extending network lifetime.
The document describes localized, self-organizing approaches for constructing energy-efficient data aggregation trees in sensor networks. It proposes Localized Power-Efficient Data Aggregation Protocols (L-PEDAPs) that use localized structures like LMST and RNG to approximate a minimum spanning tree. L-PEDAP then constructs an actual routing tree over these structures using localized parent selection strategies. Simulation results show L-PEDAP can achieve close to 90% of a theoretical upper bound on network lifetime derived in the paper, outperforming centralized solutions while meeting requirements like distributed operation, scalability, and robustness to failures.
A Survey on Clustering Techniques for Wireless Sensor Network IJORCS
This document summarizes clustering techniques for wireless sensor networks. It discusses how clustering helps improve energy efficiency and network lifetime by organizing nodes into clusters with cluster heads. The document surveys several clustering algorithms, including LEACH, DEEC, SEP, HEED, LCA, LCA2, Max-Min D-Cluster algorithm, and weighted clustering algorithms like WCA. It describes how these algorithms elect cluster heads and organize nodes into clusters using different metrics and probabilities based on remaining energy levels or node connectivity. The document concludes that clustering is a key technique for extending network lifetime in wireless sensor networks.
ENERGY EFFICIENT HIERARCHICAL CLUSTER HEAD ELECTION USING EXPONENTIAL DECAY F...ijwmn
This document summarizes an article that proposes an improved algorithm for selecting cluster heads in wireless sensor networks. The algorithm uses an exponential decay function to predict the average energy of sensor nodes and selects cluster heads based on both the probabilistic LEACH algorithm and predicted energy levels. The algorithm was tested in MATLAB simulations of a homogeneous sensor network and showed improvements in stability, average energy dissipation per round, and lifespan over the baseline LEACH protocol.
This document summarizes a research paper that proposes a new routing protocol called U-LEACH for wireless sensor networks. U-LEACH aims to prolong the lifetime of sensor networks by uniformly distributing cluster head selection throughout the network, unlike the original LEACH protocol. It describes how LEACH works and its limitations in ensuring uniform cluster head distribution. The proposed U-LEACH protocol incorporates a Uniform Distribution Technique to select cluster heads in a way that ensures each sensor node is within transmission range of a cluster head, extending the overall network lifetime.
The document discusses energy efficient routing protocols for clustered wireless sensor networks. It provides an overview of wireless sensor networks and discusses how clustering is commonly used to improve energy efficiency and scalability. The document reviews several existing clustering-based routing protocols and analyzes their approaches for prolonging network lifetime by minimizing energy consumption in wireless sensor networks.
Engineering Research Publication
Best International Journals, High Impact Journals,
International Journal of Engineering & Technical Research
ISSN : 2321-0869 (O) 2454-4698 (P)
www.erpublication.org
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.
Clustering effects on wireless mobile ad hoc networks performancesijcsit
A new era is dawning for wireless mobile ad hoc networks where communication will be done using a
group of mobile devices called cluster, hence clustered network. In a clustered network, protocols used by
these mobile devices are different from those used in a wired network; which helps to save computation
time and resources efficiently. This paper focuses on Cluster-Based Routing Protocol and Dynamic Source
Routing. The results presented in this paper illustrates the implementation of Ad-hoc On-Demand Distance
Vector routing protocol for enhancing mobile nodes performance and lifetime in a clustered network and to
demonstrate how this routing protocol results in time efficient and resource saving in wireless mobile ad
hoc networks.
1) The document proposes choosing autonomous nodes strategically to improve the robustness of coupled networks against cascading failures.
2) It shows that by selecting the 10% of nodes with highest betweenness centrality as autonomous, the robustness is significantly improved compared to random selection. This changes the percolation transition from discontinuous to continuous.
3) Even for networks with narrow degree distributions like Erdos-Renyi graphs, proper selection of autonomous nodes based on betweenness leads to large robustness gains compared to random selection.
Joint Interference Coordination and Spatial Resource ReuseIJMTST Journal
Multihop cellular networks (MCNs) have drawn tremendous attention due to its high throughput and extensive coverage. Deploying relay nodes is foreseen a cost-efficient solution to combat the severe propagation loss at cell edge. However, relay cell coverage is limited by the low transmit power, limited antenna capabilities and wireless backhaul link bottleneck which may lead to load imbalances and hence low resource utilization efficiency. Further challenges in relay deployments are attributed to increased interference levels in the network compared with macro cell-only deployments, causing degradation of the user throughput. In this context, relay cell coverage expansion and interference coordination techniques are expected to improve the performance of relay deployments. In this study, we analyze the impact of the additional interference due to the relay node transmissions. Jointly with our previous study on cell expansion, spatial resource reuse from the graph-theoretical perspective. Next, our focus shifts to developing a simple but efficient radio resource management algorithm which enables the spatial resource reuse, the pricing- based radio resource management (PRRM) strategy. The PRRM performs spatial reuse for interference-free users operating in the high signal-to-interference-and-noise ratio (SINR) region, while guaranteeing the signal quality of interference-susceptible users usually located near the coverage boundary. By applying the PRRM, we evaluate the potential benefits of the spatial resource reuse.
GPS-less Localization Protocol for Underwater Acoustic NetworksCSCJournals
The problem of underwater positioning is increasingly crucial due to the emerging importance of sub-sea activities. Knowledge of node location is essential for many applications for which sensor networks can be used. At the surface, positioning problems have been resolved by the extended use of GPS, which is straightforward and effective. Unfortunately, using GPS in the sub-sea environment is impossible and positioning requires the use of special systems. One of the major challenges in the underwater acoustic networks (UANs) area of research is the development of a networking protocol that can cope with the management of a dynamic sub-sea network. We propose a scheme to perform node discovery, using only one seed node (primary seed) in a known position. The discovery protocol can be divided into two parts: First, building up the relative co-ordinate system. Second, involving more remote nodes becoming seed nodes for further discoveries. Four different algorithms have been investigated; (i) Farthest/Farthest Algorithm, (ii) Farthest/Nearest Algorithm, (iii) Nearest/Farthest Algorithm and (iv) Nearest/Nearest Algorithm. We investigated the performances of random and fixed (grid) network topologies. Different locations of primary seed node were exercised and statistics for node discovery will be reported.
Characterization of directed diffusion protocol in wireless sensor networkijwmn
Wireless sensor network (WSN) has enormous applications in many places for monitoring the environments
of importance. Sensor nodes are capable of sensing, computing, and communicating. These sensor nodes
are energy constraint and operated by batteries. Since energy consumption is an important issue of WSN,
there have been many energy-efficient protocols proposed for the WSN. Directed diffusion (DD) is a datacentric
protocol that focuses on the energy efficiency of the networks. Since the first proposal of DD
protocol by Deborah, there have been various versions of DD protocols proposed by many scientists across
the globe. These upgraded versions of DD protocols add on various features to the original DD protocol
such as energy, scalability, network lifetime, security, reliability, and mobility. In this paper, we discuss
and classify various characteristics of themost populardirected diffusion protocols that have been proposed
over couple of years.
DEVELOPMENT OF SOM NEURAL NETWORK BASED ENERGY EFFICIENT CLUSTERING HIERARCHI...ijassn
The document summarizes a research paper that proposes a new clustering protocol called SOM-PEG for wireless sensor networks. SOM-PEG is based on the PEGASIS protocol but uses self-organizing map (SOM) neural networks to select cluster heads, with the goal of improving network lifetime and reducing energy consumption compared to PEGASIS. The document provides background on PEGASIS and SOM neural networks, describes the SOM-PEG algorithm and simulation setup, and discusses performance metrics for evaluating and comparing routing protocols in wireless sensor networks.
This document summarizes and compares various routing protocols for wireless sensor networks. It categorizes routing protocols into three types: data-centric, hierarchical, and location-based. For each type, it describes some representative protocols, outlines their advantages and disadvantages, and discusses their application domains. The document concludes that routing in wireless sensor networks faces challenges due to constraints like limited energy, bandwidth and memory in sensor nodes, and more research is still needed to develop efficient and adaptive routing techniques.
Current issue- International Journal of Advanced Smart Sensor Network Systems...ijassn
With the availability of low cost, short range sensor technology along with advances in wireless networking, sensor networks has become a hot topic of discussion. The International Journal of Advanced Smart Sensor Network Systems is an open access peer-reviewed journal which focuses on applied research and applications of sensor networks. While sensor networks provide ample opportunities to provide various services, its effective deployment in large scale is still challenging due to various factors. This journal provides a forum that impacts the development of high performance computing solutions to problems arising due to the complexities of sensor network systems. It also acts as a path to exchange novel ideas about impacts of sensor networks research.
The Wireless Sensor Network is one of the most significant purposes behind the accomplishment of long range wireless communication. Frequent connectivity failures are occurred in the sensor-organised network due to obstruction, snags, message drop because of node energy depletion; obstacle and so forth. The total communication gets collapsed if there any lessening in the nature of correspondence or quality between the sensor nodes or from the sensor nodes to the sink nodes and this prompts to connection failures. To overcome the frequent connectivity failures we propose Diminishing Connectivity Failures by Auto-Reconfiguration in WSN (DCFA). This scheme provides steadfast routes to reduce the connectivity failure and improve the network performance.
This document summarizes a research paper presented at the National Conference on Current Trends in Computer Science and Engineering. The paper proposes a Sink-initiated Geographic Multicast (SIGM) protocol for wireless sensor networks that allows mobile sinks to construct their own data delivery paths from a source node and merge these paths to form a multicast tree. This reduces location updates and achieves fast multicast tree construction and data delivery. The paper also presents a round-based virtual infrastructure to further improve the SIGM protocol's energy efficiency and ability to handle sink mobility. Simulation results show SIGM outperforms other source-initiated multicast protocols in terms of energy consumption and data delivery latency.
Data Centric Approach Based Protocol using Evolutionary Approach in WSNijsrd.com
The evolution of wireless communication and circuit technology has enabled the development of an infrastructure consists of sensing, computation and communication units that makes administrator capable to observe and react to a phenomena in a particular environment. In a Wireless Sensor Network (WSN), nodes are scattered densely in a large area. Sensor nodes can communicate with the sink node directly or through other nodes. Data transmission is the major issue in WSN. Each node has limited energy which is used in transmitting and receiving the data. Various routing protocols have been proposed to save the energy during the transmission of data. data centric approach based routing protocol which efficiently propagates information between sensor nodes in an energy constrained mode. This paper proposes a data centric routing Using evolutionary apporoach in WSN.The main objective of this protocol with evolutionary apporoach is to use artificial intelligence, to reduce the energy consumption by the nodes in transmitting and receiving the data. Implementation of Basic SEP, intelligence cluster routing and proposed protocols will be done using MATLAB.
Routing protocol on wireless sensor networkshashankcsnits
The document summarizes routing protocols for wireless sensor networks. It first defines wireless sensor networks and describes their key characteristics. It then surveys traditional routing techniques like flooding and gossiping, as well as current techniques including flat routing protocols like SPIN and directed diffusion, hierarchical routing protocols like LEACH and PEGASIS, and location-based routing protocols like GEAR. For each protocol, it provides a brief overview of how it works and compares their advantages and disadvantages. In conclusion, it states that hierarchical routing protocols generally outperform flat routing protocols, and references several papers on sensor network routing.
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.
CUTTING DOWN ENERGY USAGE IN WIRELESS SENSOR NETWORKS USING DUTY CYCLE TECHNI...ijwmn
The document summarizes an algorithm proposed to reduce energy consumption in wireless sensor networks using duty cycling and multi-hop routing. The key aspects of the algorithm are:
1) Layering the network environment based on size and identifying the optimal number of cluster heads in each layer.
2) Selecting the first layer closest to the sink as the "gateway layer" and stopping energy usage in half of these sensors to extend the network lifespan.
3) Using multi-hop routing whereby cluster heads send data to heads in the above layer until the gateway layer, which then sends to the static or mobile sink.
4) Simulation results showed the proposed algorithm performs better than LEACH and ELEACH in terms of
This document summarizes and compares the quality of service (QoS) metrics of the DSR, AODV, and RPAR routing protocols in wireless multimedia sensor networks. It discusses the hexagonal deployment of sensor nodes and evaluates the protocols based on QoS parameters like throughput, delay, dropped data ratio, network load, and retransmission attempts. The document finds that the hexagonal grid deployment and RPAR framework provide better performance compared to DSR and AODV in terms of energy efficiency and extending network lifetime.
The document describes localized, self-organizing approaches for constructing energy-efficient data aggregation trees in sensor networks. It proposes Localized Power-Efficient Data Aggregation Protocols (L-PEDAPs) that use localized structures like LMST and RNG to approximate a minimum spanning tree. L-PEDAP then constructs an actual routing tree over these structures using localized parent selection strategies. Simulation results show L-PEDAP can achieve close to 90% of a theoretical upper bound on network lifetime derived in the paper, outperforming centralized solutions while meeting requirements like distributed operation, scalability, and robustness to failures.
A Survey on Clustering Techniques for Wireless Sensor Network IJORCS
This document summarizes clustering techniques for wireless sensor networks. It discusses how clustering helps improve energy efficiency and network lifetime by organizing nodes into clusters with cluster heads. The document surveys several clustering algorithms, including LEACH, DEEC, SEP, HEED, LCA, LCA2, Max-Min D-Cluster algorithm, and weighted clustering algorithms like WCA. It describes how these algorithms elect cluster heads and organize nodes into clusters using different metrics and probabilities based on remaining energy levels or node connectivity. The document concludes that clustering is a key technique for extending network lifetime in wireless sensor networks.
ENERGY EFFICIENT HIERARCHICAL CLUSTER HEAD ELECTION USING EXPONENTIAL DECAY F...ijwmn
This document summarizes an article that proposes an improved algorithm for selecting cluster heads in wireless sensor networks. The algorithm uses an exponential decay function to predict the average energy of sensor nodes and selects cluster heads based on both the probabilistic LEACH algorithm and predicted energy levels. The algorithm was tested in MATLAB simulations of a homogeneous sensor network and showed improvements in stability, average energy dissipation per round, and lifespan over the baseline LEACH protocol.
This document summarizes a research paper that proposes a new routing protocol called U-LEACH for wireless sensor networks. U-LEACH aims to prolong the lifetime of sensor networks by uniformly distributing cluster head selection throughout the network, unlike the original LEACH protocol. It describes how LEACH works and its limitations in ensuring uniform cluster head distribution. The proposed U-LEACH protocol incorporates a Uniform Distribution Technique to select cluster heads in a way that ensures each sensor node is within transmission range of a cluster head, extending the overall network lifetime.
The document discusses energy efficient routing protocols for clustered wireless sensor networks. It provides an overview of wireless sensor networks and discusses how clustering is commonly used to improve energy efficiency and scalability. The document reviews several existing clustering-based routing protocols and analyzes their approaches for prolonging network lifetime by minimizing energy consumption in wireless sensor networks.
Energy Efficient Data Aggregation in Wireless Sensor Networks: A Surveyijsrd.com
The use of Wireless Sensor Networks (WSNs) is anticipated to bring lot of changes in data gathering, processing and dissemination for different environments and applications. However, a WSN is a power constrained system, since nodes run on limited power batteries which shorten its lifespan. Prolonging the network lifetime depends on efficient management of sensing node energy resource. Energy consumption is therefore one of the most crucial design issues in WSN. Hierarchical routing protocols are best known in regard to energy efficiency. By using a clustering technique hierarchical routing protocols greatly minimize energy consumed in collecting and disseminating data. To prolong the lifetime of the sensor nodes, designing efficient routing protocols is critical. In this paper, we have discussed various energy efficient data aggregation protocols for sensor networks.
CUTTING DOWN ENERGY USAGE IN WIRELESS SENSOR NETWORKS USING DUTY CYCLE TECHNI...ijwmn
A wireless sensor network is composed of many sensor nodes, that have beengiven out in a
specific zoneandeach of them hadanability of collecting information from the environment and
sending collected data to the sink. The most significant issues in wireless sensor networks,
despite the recent progress is the trouble of the severe limitations of energy resources.Since that
in different applications of sensor nets, we could throw a static or mobile sink, then all aspects of
such networks should be planned with an awareness of energy.One of the most significant topics
related to these networks, is routing. One of the most widely used and efficient methods of
routing isa hierarchy (based on clustering) method.
Performance Evaluation of Ant Colony Optimization Based Rendezvous Leach Usin...IJERD Editor
- The document discusses the performance evaluation of an Ant Colony Optimization (ACO) based algorithm for wireless sensor networks with mobile sinks.
- It proposes using ACO along with rendezvous points and mobile sinks in a clustering protocol called Rendezvous LEACH (RZ LEACH) to optimize energy efficiency and network lifetime.
- Simulation results show that the ACO based RZ LEACH outperforms the original RZ LEACH protocol by prolonging the number of operational nodes and increasing average remaining energy in the network over time.
Energy efficient cluster-based service discovery in wireless sensor networksambitlick
1) The document proposes an energy-efficient service discovery protocol for wireless sensor networks that exploits a cluster-based network overlay.
2) Clusterhead nodes form a distributed service registry to minimize communication costs during service discovery and maintenance.
3) The performance of the proposed integrated clustering and service discovery solution is evaluated through simulations under different network conditions.
International Journal of Advanced Smart Sensor Network Systems ( IJASSN )ijassn
This document summarizes a research paper that proposes an improved clustering technique called Optimized Fair-Zone LEACH (OFZ-LEACH) for wireless sensor networks. OFZ-LEACH uses an exponential moving average to predict node mobility and identify cluster head movement. This helps overcome issues in the original LEACH protocol like hidden clusters and link failures caused by node mobility. Simulation results show that OFZ-LEACH achieves higher packet delivery ratio, lower end-to-end delay, and extends network lifetime compared to the original LEACH and Fair-Zone LEACH protocols.
This document summarizes research on topology control techniques in wireless sensor networks. It first discusses how topology control aims to reduce energy consumption while maintaining network connectivity by regulating nodes' transmission power. It then reviews several existing topology control algorithms proposed in other papers. These algorithms distribute transmission power control to maximize network lifetime. Finally, the document concludes that many topology control algorithms have been developed to achieve energy efficient routing, but implementing them on real-world testbeds poses challenges.
CLUSTER HEAD SELECTION ALGORITHMS FOR ENHANCED ENERGY EFFICIENCY IN WIRELESS ...IJCSES Journal
The extension of the sensor node's life span is an essential requirement in a Wireless Sensor Network.
Cluster head selection algorithms undertake the task of cluster head election and rotation among nodes,
and this has significant effects on the network's energy consumption. The objective of this paper is to
analyze existing cluster head selection algorithms and the parameters they implement to enhance energy
efficiency. To achieve this objective, systematic literature review methodology was used. Relevant papers
were extracted from major academic databases Elsevier, Springer, Wiley, IEEE, ACM Digital Library,
Citeseer Library, and preprints posted on arXiv. The results show that there are many existing Cluster
Head Selection Algorithms and they are categorized as deterministic, adaptive and hybrid. These
algorithms use different parameters to elect Cluster Heads. In future the researchers should derive more
parameters that can be used to elect cluster heads to improve on energy consumption
CLUSTER HEAD SELECTION ALGORITHMS FOR ENHANCED ENERGY EFFICIENCY IN WIRELESS ...IJCSES Journal
The extension of the sensor node's life span is an essential requirement in a Wireless Sensor Network.
Cluster head selection algorithms undertake the task of cluster head election and rotation among nodes,
and this has significant effects on the network's energy consumption. The objective of this paper is to
analyze existing cluster head selection algorithms and the parameters they implement to enhance energy
efficiency. To achieve this objective, systematic literature review methodology was used. Relevant papers
were extracted from major academic databases Elsevier, Springer, Wiley, IEEE, ACM Digital Library,
Citeseer Library, and preprints posted on arXiv. The results show that there are many existing Cluster
Head Selection Algorithms and they are categorized as deterministic, adaptive and hybrid. These
algorithms use different parameters to elect Cluster Heads. In future the researchers should derive more
parameters that can be used to elect cluster heads to improve on energy consumption.
IJERD (www.ijerd.com) International Journal of Engineering Research and Devel...IJERD Editor
SEECH is a secure and energy efficient centralized routing protocol for hierarchical wireless sensor networks. It utilizes a base station to efficiently form clusters based on sensor node energy levels and neighbor information. The base station selects cluster heads that have above average energy and many neighbors. Cluster heads then schedule sensor node transmissions to reduce interference and aggregate and encrypt sensor data before transmitting to the base station or other cluster heads. SEECH aims to prolong network lifetime by minimizing energy consumption through efficient clustering and routing.
The Energy hole problem is a major problem of
data collection in wireless sensor networks. The sensors near the
static sink serve as relays for remote sensors, which reduce their
energy rapidly, causing energy holes in the sensor field. This
project has proposed a customizable mobile sink based adaptive
protected energy efficient clustering protocol (MSAPEEP) for
improvement of the problem of energy holes along with that we
also characterize and made comparison with the previous
existing protocols. A MSAPEEP uses the adaptive protected
method (APM) to discover the best possible number of cluster
heads (CHs) to get better life span and constancy time of the
network. The effectiveness of MSAPEEP is compared with
previous protocols; specifically, low energy adaptive clustering
hierarchy (LEACH) and mobile sink enhanced energy efficient
PEGASIS based routing protocol using network simulator(NS2).
Examples of simulation result show that MSAPEEP is more
reliable and removes the potential of energy hole and enhances
the stability and life span of the wireless sensor network(WSN).
Iaetsd survey on wireless sensor networks routingIaetsd Iaetsd
This document summarizes and compares several hierarchical routing protocols for wireless sensor networks that aim to improve energy efficiency. It discusses LEACH, HEED, PEGASIS, TBC and TREEPSI protocols. These protocols use clustering and data aggregation techniques to reduce energy consumption and prolong network lifetime. Simulation results show that these hierarchical protocols can achieve better energy efficiency and balance energy loads compared to traditional routing protocols. The document also analyzes the advantages and disadvantages of the LEACH protocol in detail.
ENERGY OPTIMISATION SCHEMES FOR WIRELESS SENSOR NETWORKcscpconf
A sensor network is composed of a large number of sensor nodes, which are densely
deployed either inside the phenomenon or very close to it. Sensor nodes have
sensing, processing and transmitting capability . They however have limited energy
and measures need to be taken to make op- timum usage of their energy and save
them from task of only receiving and transmitting data without processing. Various
techniques for energy utilization optimisation have been proposed Ma jor players are
however clustering and relay node placement. In the research related to relay node
placement, it has been proposed to deploy some relay nodes such that the sensors
can transmit the sensed data to a nearby relay node, which in turn delivers the data
to the base stations. In general, the relay node placement problems aim to meet
certain connectivity and/or survivabil- ity requirements of the network by deploying a
minimum number of relay nodes. The other approach is grouping sensor nodes into
clusters with each cluster having a cluster head (CH). The CH nodes aggregate the
data and transmit them to the base station (BS). These two approaches has been
widely adopted by the research community to satisfy the scala- bility objective and generally achieve high energy efficiency and prolong network lifetime in large-scale WSN environments and hence are discussed here along with single hop and multi hop characteristic of sensor node
Bottleneck Detection Algorithm to Enhance Lifetime of WSNjosephjonse
In recent years, a wireless sensor network is gaining much more importance due to its immense contribution in numerous applications. Deployment of sensor nodes that would reduce computation, minimize cost and gaining high degree of network connectivity is an challenging task. Random deployment of sensor nodes causes the wireless sensor networks to face topological weaknesses such as communication bottlenecks, network partitions and sensing holes. These problems lead to uneven energy utilization, reduction in reliability of network and reduction in network lifetime. Bottleneck detection algorithm is proposed to identify bottleneck and minimal bottleneck zones in network. Additional sensor node deployment strategy is used in bottleneck detection algorithm to extend network lifetime. Random additional sensor node deployment and Targeted additional sensor node deployment are proposed to enhance network lifetime. Deployment strategies are compared with respect to network parameters such as throughput, packet delivery fraction and network lifetime.
Bottleneck Detection Algorithm to Enhance Lifetime of WSNjosephjonse
In recent years, a wireless sensor network is gaining much more importance due to its immense contribution in numerous applications. Deployment of sensor nodes that would reduce computation, minimize cost and gaining high degree of network connectivity is an challenging task. Random deployment of sensor nodes causes the wireless sensor networks to face topological weaknesses such as communication bottlenecks, network partitions and sensing holes. These problems lead to uneven energy utilization, reduction in reliability of network and reduction in network lifetime. Bottleneck detection algorithm is proposed to identify bottleneck and minimal bottleneck zones in network. Additional sensor node deployment strategy is used in bottleneck detection algorithm to extend network lifetime. Random additional sensor node deployment and Targeted additional sensor node deployment are proposed to enhance network lifetime. Deployment strategies are compared with respect to network parameters such as throughput, packet delivery fraction and network lifetime.
Investigation of energy efficient protocols based on stable clustering for en...journalBEEI
There are certain challenges faced with wireless sensor networks (WSNs) performances, consumption can be seen amongst all these challenges as a serious area of research. Data from sensor nodes are transmitted by most WSN energy either among many nodes or to the base station (BS), and due this connection, several routing protocols were developed for supporting in data transmission in the WSNs. Extending network lifetime in an operational environment is the major objective of the wireless sensor network. Charging or exchanging sensor node batteries is almost impossible. Energy balancing and energy efficiency are significant research scopes as per designing of routing protocols aimed at self-organized WSNs. A heterogeneous WSN is one where every node has different amount of energy linked to it before it is deployed in a network. Therefore, different energy efficient routing protocols have been proposed which enables lesser consumption of energy, longer stability period which leads to the network lifetime increasing. In this study, the average energy of a WSN is computed after every logical round of operation for our protocol-HPEEA and compare it with two well-known heterogeneous protocols namely-SEP and CCS. At the end of the considered number of logical operations, MATLAB with simulation results confirm that HPEEA protocol have a reduction in the energy consumption compared to other protocols.
INCREASING WIRELESS SENSOR NETWORKS LIFETIME WITH NEW METHODijwmn
The document proposes a new method to increase the lifetime of wireless sensor networks. It divides the sensor network environment into two virtual layers based on distance from the base station. It then uses residual energy, distance from base station, and position in the layers as factors in selecting cluster heads. Simulations show the proposed method outperforms LEACH and ELEACH algorithms in both homogeneous and heterogeneous sensor energy environments.
Similar to Node clustering in wireless sensor (20)
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2. YOUNIS LAYOUT 5/3/06 2:24 PM Page 21
Intercluster Intracluster
communication communication
• Every node has a unique identifier.
• These identifiers are uniformly assigned throughout the
field.
For example, the scheme in [4] favors nodes with lower identi-
fiers to become CHs. This approach may not be suitable for
energy-constrained sensor networks because it penalizes spe-
cific nodes in the network irrespective of their battery life-
times.
Mobile
Another class favors nodes with larger degrees (e.g., Kuhn
observer et al. [5] and Amis et al. [6]) in order to create dense clusters
and elect the minimal dominating set of CHs (the degree of a
node is the number of its neighbors within a prespecified
transmision called the cluster range). This, however, may result
I Figure 1. Illustration of data flow in a clustered network. in quickly draining the battery of larger-degree nodes. From
an application perspective, balancing cluster sizes reduces the
load on CHs. However, this comes at the expense of having
tery power with limited energy. Hence, the employed cluster- more clusters in the network and thus a larger routing overlay.
ing approach must have low message overhead. Finally, harsh A third class of techniques favors nodes with higher weights to
environmental conditions result in unexpected failures of become CHs. The weight of the node is used to define its sig-
nodes. Hence, periodic reclustering is necessary in order to nificance. For example, it can be the residual battery energy
heal disconnected regions and distribute energy consumption (as in the HEED protocol [3]), its degree (as in the ACE pro-
across all nodes. Periodic reclustering is also necessary, as the tocol [7]), or a combination of parameters (e.g., remaining
parameters used for clustering (e.g., the remaining energy, energy, degree, mobility, and average distance to neighbors).
node degree, etc.) are dynamic. The clustering techniques pro- Some protocols, such as GAF [8] and SPAN [9], were pro-
posed for data processing typically consider static parameters, posed for controlling the network topology by exploiting node
such as the distance between the nodes, and assume that redundancy. These protocols select certain nodes to be active
nodes are more reliable. (i.e., participate in sensing and data forwarding), while others
The goal of this article is to introduce the reader to different are put to sleep to save their energy. In GAF [8], for example,
classes of clustering approaches that have been proposed for a node belongs to a region that is determined by its location.
WSNs. We compare some representative protocols in terms of A region in this context is defined as an area A in which any
their design approach, clustering criteria, basic assumptions, node u can communicate via a single hop with any node v ∈
and overhead. We consider clustering proposals that target the B, where B is a neighboring region to A. Thus, only one repre-
general class of ad hoc networks and are also suitable for sen- sentative node in any region needs to participate in the rout-
sor networks. This article focuses more on clustering “approach- ing infrastructure at any given time to ensure network
es” than on “protocols.” A clustering “approach” in this context connectivity. In SPAN [9], a node decides whether to remain
identifies the parameter(s) used for partitioning the network active or go to sleep according to its two-hop neighborhood
and whether clustering is performed in a centralized or a dis- connectivity. Although these protocols are not clustering tech-
tributed fashion. In addition, we highlight the basic challenges niques, their effect on the network topology is similar to that
in deploying clustering techniques in WSNs. of clustering.
Execution of a Clustering Algorithm
Classification of Clustering Techniques in The execution of a clustering algorithm can be carried out at
a centralized authority (e.g., a base station) or in a distributed
Wireless Sensor Networks way at local nodes. Centralized approaches require global
Clustering in WSNs involves grouping nodes into clusters and
electing a CH such that:
• The members of a cluster can communicate with their CH 100
directly. 90
• A CH can forward the aggregated data to the central base LEACH
station through other CHs. 80
Thus, the collection of CHs in the network form a connected
70 MTE
dominating set. Research on clustering in WSNs has focused
Number of nodes alive
on developing centralized and distributed algorithms to com- 60
pute connected dominating sets. We focus on distributed
approaches in this article since they are more practical for 50
large-scale deployment scenarios. Since obtaining an optimal
40
dominating set is an NP-complete problem, the proposed
algorithms are heuristic in nature. Static LEACH-C
30
clustering
We classify the clustering techniques based on two criteria:
• The parameter(s) used for electing CHs 20
• The execution nature of a clustering algorithm (probabilistic
10
or iterative)
0
Election of Cluster Heads 0 100 200 300 400 500 600 700 800 900 1000
One class of clustering techniques uses the node identifier to Time (s)
elect CHs. The success of this approach depends on two
assumptions: I Figure 2. Number of nodes that remain alive over time [2].
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3. YOUNIS LAYOUT 5/3/06 2:24 PM Page 22
information about the network topology. The classic K-Means The LEACH protocol [2] is an application-specific clus-
clustering approach (proposed in the data processing litera- tering protocol, which has been shown to significantly
ture) may be applied if the number of desired clusters can be improve the network lifetime. It assumes that every node is
determined a priori and node locations are available. In this reachable in a single hop and that load distribution is uni-
case, an initial random set of clusters is selected and a node is form among all nodes. LEACH assigns a fixed probability to
moved from one cluster to another if this move reduces the every node so as to elect itself as a CH. The clustering pro-
objective cost function of the entire system. Banerjee et al. cess involves only one iteration, after which a node decides
[10] proposed a centralized technique that does not require whether to become a CH or not. Nodes take turns in carry-
knowledge of node locations. Their technique is based on con- ing the role of a CH.
structing a spanning tree of clusters that is rooted at an The HEED protocol [3] considers a multihop network
observer and forcing a bound on the maximum and minimum and assumes that all nodes are equally important. A node
cluster size. A distributed protocol was also proposed in [10] uses its residual energy as the primary parameter to proba-
for constructing the spanning tree. bilistically elect itself to become a CH. In case of a tie
The efficacy of centralized approaches is limited in large- between two CHs, say u and v, u concedes to v (i.e., gives
scale networks where collecting all the necessary information up its CH candidacy) according to a secondary parameter,
at the central authority is both time and energy consuming. such as node degree or average distance to neighbors. This
Distributed (localized) approaches are more suitable for results in the uniformly distribution of the elected set of
large-scale networks. In such approaches, a node decides to CHs across the network. In HEED, each node executes a
join a cluster or become a CH based on the information constant number of iterations. An implementation of HEED
obtained solely from its one-hop neighbors. Several distribut- in TinyOS (the operating system for Berkeley motes)
ed clustering techniques have been proposed in the literature. showed that clustering and data aggregation at least double
These techniques are either iterative or probabilistic in nature. the network lifetime.
Kuhn et al. [5] proposed a probabilistic technique to elect
Iterative Clustering Techniques — In iterative clustering tech- CHs, in which the probability is dependent on the node
niques, a node waits for a specific event to occur or certain degree. The convergence of their proposed technique, which
nodes to decide their role (e.g., become CHs) before making depends on the number of nodes in the network and the node
a decision. For example, in the Distributed Clustering Algo- degree, is much faster than iterative techniques. In addition,
rithm (DCA) [11], before making a decision, a node waits for this approach elects a dominating set of CHs that is asymptot-
all its neighbors with higher weights to decide to be CHs or ically optimal (minimal).
join existing clusters. Nodes possessing the highest weights in Table 1 compares representative examples of distributed
their one-hop neighborhoods are elected as CHs. If a node clustering techniques. (Note that several other techniques
receives multiple CH announcements, it arbitrates among were proposed in the literature but are not discussed here due
these CHs using a preference condition (e.g., higher weight to space limitations.) The table shows that all distributed clus-
wins). If none of the higher-weight neighbors of a node tering protocols have a constant message overhead per node.
decides to become a CH, then this node decides to become a This is an important advantage of the distributed techniques
CH. The problem with most iterative approaches is that their over the centralized ones, which involve significant message
convergence speed is dependent on the network diameter overhead. The processing overhead at each sensor, however,
(path with the largest number of hops). In a two-dimensional is negligible in a centralized approach compared to a dis-
field with n deployed nodes, the DCA algorithm requires tributed one (in which nodes participate in the computations).
For example, in iterative approaches, a node has to check the
O ( n) received messages to decide how it should react. These mes-
sages can be O(δ), where δ is the node degree. As energy con-
iterations to terminate. The worst-case convergence speed can sumption for data processing is typically lower than that for
be as slow as n – 1 iterations in a 1D setting. The perfor- communication, the message processing overhead may be
mance of iterative techniques is also highly sensitive to packet ignored.
losses. For example, if a node u discovers that one of its As shown in Table 1, most of the distributed protocols have
neighbors v has a higher weight, then u has to wait for v to low overhead. This overhead is dependent on the frequency of
decide before it makes a decision. If node v fails shortly after reclustering, which is small in typical applications. Throughput
the neighborhood discovery phase, node u will wait indefinite- is typically not negatively affected by clustering, as shown in
ly for v to make a decision. an implementation study of HEED [3]. In fact, throughput is
To ameliorate the above problems, some protocols enforce improved under high load because of the reduction in channel
a bound on the number of iterations for each node. For exam- contention. The performance of each clustering protocol
ple, in ACE [7] when a node finishes executing a number of depends on the network configuration, the system model, and
iterations (e.g., 5), it makes a decision based on the available the application scenario.
information. These iterations are enough to achieve a stable
average cluster size. The protocol in [6] allows a cluster to
include nodes that are D hops away from the CH. A node
Open Issues
executes 2D iterations before making a decision. This results Clustering in WSNs faces several deployment challenges, such
in a constant number of iterations for convergence. as ensuring connectivity, selecting the optimal frequency of
CH rotation, computing the optimal cluster sizes, and cluster-
Probabilistic Clustering Techniques — The probabilistic (or ran- ing the network in the presence of a node duty cycle. 1
domized) approach for node clustering ensures rapid conver- Addressing these problems will require cross-layer design,
gence while achieving some favorable properties, such as especially with regard to the MAC and network layers.
balanced cluster sizes. It enables every node to independently
decide on its role in the clustered network while keeping the
message overhead low. We now discuss a few examples of this 1 In a typical WSN, a sensor alternates between active and sleep states. The
approach. ratio of the active time to the total time is referred to as the node duly cycle.
22 IEEE Network • May/June 2006
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4. YOUNIS LAYOUT 5/3/06 2:24 PM Page 23
Complexity (per node)
Protocol I/P Cluster criteria Objective Assumptions
Time (iter.) Message
Unique node identifiers
Baker et al. [4] I Identifier Minimum dominating set and uniform node O(Diam) O(1)
distribution
Topology and field
GAF [8] I Position Redundancy elimination O(1) O(1)
dimensions are known
Two-hop Every node has a routing Routing protocol
SPAN [9] I Redundancy elimination O(1)
connectivity table overhead
Dominating set of high- Unique, real value
DCA [11] I Weight O(Diam) O(1)
er-weight nodes weight for every node
Max-Min D-hop cluster formation, MAC layer provides
I Degree O(D) O(D)
D-Cluster [6] D is a constant collision avoidance
Rapid convergence, Nonuniform load distru-
ACE [7] I Degree O(1) O(1)
denser cluster sizes bution
Rapid convergence and Single-hop network and
LEACH [2] P CH frequency maximized network life- uniform load distribu- O(1) O(1)
time tion
Rapid convergence and
Nonuniform load distri-
HEED [3] P Residual energy mazimized network life- O(1) O(1)
bution
time
Three independent com-
Kuhn et al. [5] P Degree Minimum dominating set polylog(n) polylog(n))
munication channels
I Table 1. Comparison of representative distributed clustering techniques. I/P denotes whether a protocol is iterative or probabilistic,
Diam denotes the network diameter, and n denotes the number of nodes in the network.
Connectivity MAC Layer Design
An important objective of any clustering technique is network Scheduling intracluster and intercluster transmissions is
connectivity. For intracluster communication, a cluster mem- another important design challenge. Since clustering is typical-
ber communicates with its CH either directly (e.g., [2, 3, 7]) or ly employed in applications where data aggregation is per-
via multiple hops (e.g., [6, 11]). Connectivity in this case is a formed, time division multiple access (TDMA) is best for
result of the success of cluster formation. For intercluster com- intracluster transmissions. This is because a CH can set the
munication, two approaches were adopted in order to maintain TDMA schedule and inform its cluster members about it. The
connectivity. In one approach (e.g., [6, 10, 11]), nodes on clus- problem is how to prevent the TDMA intracluster transmis-
ter boundaries are used as gateways to relay data among CHs. sions from colliding with transmissions in neighboring clusters
This approach (depicted in Fig. 3a) is suitable in networks that or with intercluster frames, especially when CHs use longer
use a fixed transmission power. Network density has to be suf- ranges for communicating with each other. One possible solu-
ficiently high in order to ensure that enough gateways are pre- tion is to use orthogonal frequency channels or different
sent at the intersection areas between clusters. In another CDMA codes to parallelize intracluster and intercluster trans-
approach (e.g., [2, 3]), the CH overlay constitutes the routing missions. It may not be cost effective, however, to equip cheap
infrastructure, and intercluster routing proceeds only through sensors with expensive radios in order to support orthogonal
CHs. This approach (depicted in Fig. 3b) is appropriate if: channels or codes. Enabling concurrent intracluster and inter-
• A node can tune its transmission power 2 (e.g., Berkeley cluster communications using a single radio channel is an
motes). open research issue.
• The CH density and intercluster transmission range satisfy
the connectivity conditions specified by Gupta and Kumar Rotating the Role of Cluster Heads
[12]. It is essential to rotate the role of CHs among nodes so as not
An advantage of this approach is that it enables all non-CHs to burden a few nodes with more duties than others. There
to sleep while not sensing or transmitting. Selecting the opti- are several possibilities for CH rotation. One way is to use a
mal intracluster and intercluster transmission ranges to ensure timer expiration to trigger the clustering algorithm, as
connectivity and prolong the network lifetime is still an open described in “Node Synchronization” below. Another way is
issue. to use a dynamic parameter (e.g., remaining battery) for trig-
gering the clustering algorithm at local regions. For example,
a CH might trigger a new CH election process in its local
2Note that power control in WSNs is used for switching between CH and region if its remaining battery lifetime goes below a prespeci-
non-CH operation modes, and not on a per-packet basis, as proposed for fied threshold. The CH rotation mechanism is typically inde-
more capable ad hoc networks. pendent of the clustering protocol.
IEEE Network • May/June 2006 23
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5. YOUNIS LAYOUT 5/3/06 2:24 PM Page 24
+ + + +
+ + + +
GN
+ + + +
+ + + +
GN
+ CH + CH
Pressure + GN Pressure + CH
CH
sensor + sensor +
+ GN + GN + +
+ GN +
+ +
Base Base
+ + GN station + + station
+ +
CH CH
+ CH + CH
+ + + +
+ +
(a) (b)
I Figure 3. Intercluster connectivity models: a) routing via gateway nodes; b) routing via CHs only. GN: gateway node.
It is obvious that more frequent CH rotation results in intercluster traffic and hence will deplete their batteries faster
more clustering overhead and network interruption, while less than faraway CHs). In order to balance energy consumption
frequent rotation may cause some nodes to die faster than among CHs, both intracluster aggregation and the data for-
others. The study of this trade-off is essential for achieving warding responsibilities of a CH have to be considered. Shu et
optimal network lifetime. Currently, applications set this rota- al. [13] studied how to achieve this balance by assigning larger
tion frequency heuristically, based on some intuitive factors cluster sizes to CHs that are responsible for less data forward-
such as the expected battery lifetime and the node degree. ing. An example is illustrated in Fig. 4, in which sensors are
deployed in a circular region around a base station. This
Node Duty Cycle approach is constrained by the maximum possible sensor-
A primary factor that prolongs the battery lifetime is allowing transmission range, and the supporting MAC layer. The read-
sensors to sleep when not active. This is due to the following er is referred to [13] and the references therein for more
three reasons. First, idle listening consumes significant energy information on load- and power-balanced clustering tech-
that is comparable to transmission or reception. For example, niques in WSNs. Several issues are still open for research,
in a Berkeley Mica2 mote, idle listening consumes energy including how to optimally select cluster sizes without knowl-
close to that of reception. In contrast, the energy drainage
during sleep time is about three orders of magnitude less than
the reception energy consumption. Second, battery discharge
is nonlinear, and some of the unusable charges can be restored
in the battery after the sleeping period. Third, sensors are typ-
ically deployed redundantly, which implies that not all the
nodes need to be awake simultaneously.
Therefore, clustering techniques should incorporate the
node’s duty cycle in their design. This can be done in one
of two ways, depending on the type of the application.
First, non-CH nodes can be allowed to sleep when they are
not sensing or communicating with their CHs. This
approach is suitable for applications where sensors are
periodically sending reports. Second, if the application
requires the sensors to continuously monitor the field for
unexpected events, then a CH can determine which of its
cluster members are redundant and advise them to turn
themselves off. Thus, a CH maintains a minimal active set
of nodes in the cluster. It is also possible to elect an active
set of nodes to cover the field prior to cluster formation. In
this case, the CH and all its members are active during the
network operation cycle.
Optimal Cluster Size
Currently, most clustering protocols assume a fixed cluster-
transmission range, which results in uniform cluster sizes.
However, this results in a skewed load distribution on CHs I Figure 4. Selecting cluster sizes to evenly distribute energy con-
(e.g., CHs that are closer to the observer will carry more sumption among CHs.
24 IEEE Network • May/June 2006
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6. YOUNIS LAYOUT 5/3/06 2:24 PM Page 25
edge of the node locations and how to exploit knowledge of [5] F. Kuhn, T. Moscibroda, and R. Wattenhofer, “Initializing Newly Deployed Ad Hoc
the locations of data sinks for efficient cluster formation. and Sensor Networks,” Proc. ACM MOBICOM, Sept. 2004, pp. 260–74.
[6] A. D. Amis et al., “Max-Min D-Cluster Formation in Wireless Ad Hoc Net-
works,” Proc. IEEE INFOCOM, Mar. 2000, pp. 32–41.
Node Synchronization [7] H. Chan and A. Perrig, “ACE: An Emergent Algorithm for Highly Uniform Cluster
Distributed clustering protocols achieve their best perfor- Formation,” Proc. 1st Euro. Wksp. Sensor Networks, Jan. 2004, pp. 154–71.
mance when sensor nodes are synchronized. Node synchro- [8] Y. Xu, J. Heidemann, and D. Estrin, “Geography-Informed Energy Conserva-
tion for Ad Hoc Routing,” Proc. ACM MOBICOM, Rome, Italy, July 2001,
nization ensures that the clustering process starts pp. 70–84.
simultaneously throughout the network. Lack of synchroniza- [9] B. Chen et al., “SPAN: An Energy-Efficient Coordination Algorithm for Topol-
tion may result in a suboptimal choice of CHs, especially for ogy Maintenance in Ad Hoc Wireless Networks,” ACM Wireless Networks,
probabilistic approaches. However, the clustering process can vol. 8, no. 5, Sept. 2002, pp. 481–94.
[10] S. Banerjee and S. Khuller, “A Clustering Scheme for Hierarchical Control in Mul-
be triggered by nodes with faster clocks. This happens when tihop Wireless Networks,” Proc. IEEE INFOCOM, Apr. 2001, pp. 1028–37.
such nodes start querying their neighbors for updated infor- [11] S. Basagni, “Distributed Clustering Algorithm for Ad Hoc Networks,” Proc. Int’l.
mation in order to start the clustering process. Received Symp. Parallel Architectures, Algorithms, and Networks, 1999, pp. 310–15.
queries trigger the clustering process at these neighbors, and [12] P. Gupta and P. R. Kumar, “Critical Power for Asymptotic Connectivity in
Wireless Networks,” Stochastic Analysis, Control, Optimizations, and Appli-
these neighbors in turn trigger their neighbors, and so on. cations: A Volume in Honor of W. H. Fleming, W. M. McEneaney, G. Yin,
Note that it is not essential that “all” the nodes in the network and Q. Zhang, Eds., Birkhauser, 1998.
start the clustering process simultaneously. In fact, it is suffi- [13] T. Shu, M. Krunz, and S. Vrudhula, “Power Balanced Coverage Time Opti-
cient that the process starts in different regions (nodes within mization for Clustered Wireless Sensor Networks,” Proc. ACM Int’l. Symp.
Mobile and Ad Hoc Networking and Comp., May 2005, pp. 111–20.
one or two hops) simultaneously. Probabilistic techniques that
use a number of iterations (e.g., [3, 5]) are therefore less Biographies
impacted by the lack of synchronization than single-iteration OSSAMA YOUNIS [M] (younis@ece.arizona.edu) is an assistant research scientist
techniques (e.g., [2]). in computer engineering at the University of Arizona. He received B.S. and M.S.
degrees with honors in computer science from Alexandria University, Egypt, in
1995 and 1999, respectively, and his Ph.D. degree in computer science from
Conclusions Purdue University in August 2005. He has served on the Technical Program
Committee for several international conferences, such as AINA 2006, WoW-
Node clustering is a useful topology-management approach to MoM 2006, WWIC ’06, and ICWMC ’06. His research interests include wireless
reduce the communication overhead and exploit data aggrega- sensor network protocols and applications, Internet tomography, and video com-
tion in sensor networks. We have classified the different clus- munication. He is a member of the ACM.
tering approaches according to the clustering criteria and the MARWAN KRUNZ (krunz@ece.arizona.edu) is an associate professor of electrical
entity responsible for carrying out the clustering process. We and computer engineering at the University of Arizona. He received a Ph.D.
have focused on distributed clustering approaches, which are degree in electrical engineering from Michigan State University in 1995. From
more suitable for large-scale sensor networks. We highlighted 1995 to 1997 he was a postdoctoral research associate with the Department of
Computer Science, University of Maryland, College Park. He also held visiting
some of the basic challenges that have hindered the use of research positions at INRIA, Sophia Antipolis, France; HP Labs, Palo Alto, CA;
clustering in current applications. We surmise that the most and US West Advanced Technologies, Boulder, CO. His recent research interests
compelling challenges are how to schedule concurrent intra- include medium access and routing protocols for mobile ad hoc networks, quality
cluster and intercluster transmissions, how to compute the of service provisioning over wireless links, constraint-based routing, Web traffic
modeling, and media streaming. He has published more than 100 journal articles
optimal cluster size, and how to determine the optimal fre- and refereed conference papers in these areas. He received the National Science
quency for CH rotation in order to maximize the network life- Foundation CAREER Award (1998–2002). He currently serves on the editorial
time. boards of IEEE/ACM Transactions on Networking, IEEE Transactions on Mobile
Computing, and Computer Communications Journal. He has been a guest editor
for special issues of IEEE Micro and IEEE Communications Magazine. He served
References as technical program co-chair for IEEE INFOCOM 2004, IEEE SECON 2005,
[1] “Habitat Monitoring on Great Duck Island,” http://www.greatduck IEEE WoWMom 2006, and the 2001 Hot Interconnects Symposium. He consults
island.net/, 2006. for a number of corporations in the telecommunications industry.
[2] W. Heinzelman, A. Chandrakasan, and H. Balakrishnan, “An Application-
Specific Protocol Architecture for Wireless Microsensor Networks,” IEEE SRINIVASAN RAMASUBRAMANIAN (srini@ece.arizona.edu) is an assistant professor
Trans. Wireless Commun., vol. 1, no. 4, Oct. 2002, pp. 660–70. in the Department of Electrical and Computer Engineering at the University of
[3] 0. Younis and S. Fahmy, “Distributed Clustering in Ad Hoc Sensor Networks: Arizona. He received a B.E. (honors) degree in electrical and electronics engi-
A Hybrid, Energy-Efficient Approach,” Proc. IEEE INFOCOM, Hong Kong, neering from Birla Institute of Technology and Science, Pilani, India, in 1997,
Mar. 2004; an extended version appeared in IEEE Trans. Mobile Comp., and a Ph.D. degree in computer engineering from Iowa State University, Ames,
vol. 3, no. 4, Oct.–Dec. 2004, pp. 366–79. in 2002. His research interests include architectures and algorithms for optical
[4] D. J. Baker and A. Ephremides, “The Architectural Organization of a Mobile networks, computer communication networks and protocols, fault tolerance, sys-
Radio Network via a Distributed Algorithm,” IEEE Trans. Commun., vol. 29, tem modeling, and performance analysis. He served as the TPC Co-Chair for
no. 11, 1981, pp. 1694–701. BROADNETS 2005 and is an editor of Wireless Networks Journal.
IEEE Network • May/June 2006 25
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