wireless sensor network lifetime constraints

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Wireless Sensor Network Lifetime Constraints

Musaab M. JasimYildiz universityComputer department

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Outline Introduction of WSN. Generic energy consumption of WSN . WSN Deployments

Deterministic deployment . Random deployment .

WSN Routing Protocols WSN Routing Strategies . Routing Protocols in WSNs.

Energy- Efficient Routing Protocol Algorithms LEACH (Low Energy Adaptive Clustering Hierarchy). DECSA (Distance-Energy Cluster Structure Algorithm).

Conclusion .

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Introduction of WSN

Introduction of WSN

The convergence of the Internet, communications, and information technologies,

coupled with recent engineering advances, is paving the way for a new generation

of inexpensive sensors and actuators, capable of achieving a high order of spatial

and temporal resolution and accuracy and this generation of devices led to widely

distribution of the Wireless Sensor Network (WSN) in recent years . WSNs have

become a subject of interest for many different applications .

A wireless sensor network is an infrastructure comprised of large numbers of nodes

which involve sensing (measuring), computing, and communication elements that

gives an administrator the ability to instrument, observe, react to events and

phenomena in a specified environment where these nodes are deployed. These

nodes fall in two types

(1) sensor node which gather the sensing data and direct it to

(2) sink node which be interested for this data .4

Introduction of WSN

the both types of nodes are limited in their power resources because it usually run

on batteries and this imposes a hard limit on the lifespan of a WSN especially for

large-scale WSNs when it integrate with other networks .

To maximize the lifetime of WSN , we need to comprehend some important aspects

,such as : how the power of nodes is consumed in general form , what the influence

of the nodes deployment ways on the node's power is , and the major role of

routing protocol on manage the WSNs and minimize the energy consumption.

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Generic energy consumption of WSN

Generic energy consumption of WSN. The major energy consumption of a node (usually in free rectangular area)

includes the energy which is consumed for:1. message reception .2. message transmission .3. event sensing.

The energy for event sensing is generally linearly proportional to the time period of operation and is assumed to be

The energy for message reception depends only on the number of received messages.

the energy dissipation for transmitting a message to a receiver with a distance (d) away being

the energy dissipation for receiving a message is

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is the average power consumption.

is a time interval.

L(d) denotes the propagation loss in DB

L(d0) the propagation loss at a reference distance

Βk

the path loss exponentsensing message bits

Eelec energy consumption by the electronic circuit

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WSN Deployments

WSN Deployments Deployment is application dependent process which concerned with

setting up an operational sensor network in a real-world environment to provide completely area coverage with different levels of nodes density and take into account that each sensor has a probability (P) to be active and it can be cover a circular region centered at itself with radius (r) , There are two major sorts of deployment are distinguished in WSNs :

1. Deterministic deployment the deployment method in which the nodes of WSN are distributed in a structured way by putting them in pre-planned positions. There are many models of this deployment such as :

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B- Grid-based deployment A- Linear-based deployment .

Square Grid

WSN Deployments

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B- Grid-based deployment

Equilateral Triangle grid Deployment

Tri-Hexagon Tiling (THT).

2. Random deployment The deployment methods in which the nodes of WSN are randomly distributed over the desired area by, e.g., dropping them out of an helicopter as in the volcano monitoring system or in a hostile environment .It may be a one-time activity where the installation and use of a sensor network are strictly separate actions. Or, it may be a continuous process, with more nodes being deployed at any time during the use of the network . there two types of random deployment :

WSN Deployments

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Random deployment types

II. Non-uniform random deployment I. Uniform random deployment

• It deployment of WSN nodes in different density level over the entire sensing area ,where all nodes in the network are homogeneous with the same available energy .

• It attempts to balance the communication load of each sub-region.

• It is considered as the solution of the “Energy Holes problem” , where nodes are deployed with a high density on a location with high energy consumption, whereas, a low density for a location with low energy consumption .

• It is deployment of WSN nodes in randomly fashion with the same density over the entire sensing area, where all nodes are homogeneous with the same available energy .

• It can achieve the best network sensing coverage in the initial phase.

• It suffers from the “Energy Holes problem” , where nodes located at an area with high energy consumption will run out of available energy and die off quickly .

WSN Deployments

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Models

Non-uniform random deploymentRectangle model

Uniform random deploymentCoronas Model

where the desired sensing area is assumed to be a rectangle with length L and width W, i.e. the area is A = L × W. and the data sink is assumed to be beside an edge of the sensing area as base-station, and the sensor node deploy in non-uniform random way with sensing radius is R and available sensing area is πR2.

A message transmitted from corona Ci is forwarded by sensor nodes in coronas Ci−1, Ci−2, and so on until it reaches corona C1 from where it is transmitted to the sink which reside in the center. Corona width is chosen such that a message is forwarded by only one sensor in each corona.

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WSN Routing Protocols

WSN Routing ProtocolsRouting protocols in WSN It play a major role in managing the network , since the different

data forwarding mechanisms lead to different amount and different distribution of energy consumption in WSN. So, the good choice of routing protocol for the certain types of deployment under particular radio features plays the main role in saving the nodes power , thus maximize of the WSN lifespan

The routing protocol in WSN has extra tasks in addition to its ordinary tasks to provide shortest path between source and destination , as shown below :

1. minimizing energy consumed per packet .2. maximize time to network partition .3. minimizing variance in node power levels .4. minimizing maximum node cost . so , it are considered the substantial responsible about the network lifespan .

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WSN Routing ProtocolsWSN Routing Strategies At present , array of routing protocols for WSNs are existent,

which use different strategies to address one or more of the restrictions and the most commonly utilized strategies are :1. Flooding strategy: it means that every node which

receives new information will forward it to all its neighbors until it reaches its destination ,such as: Temporally-Ordered Routing Algorithm(TORA).

2. Interest advertisement-request strategy: In this routing protocol strategy the information is described by meta-data which initially is exchanged between the nodes. Nodes which acquired new data advertise it via its meta-data classification. Neighboring nodes which have an interest in that kind of data reply with a request, achieves a high energy efficiency compared to flooding strategy, such as: Sensor Protocols for Information via Negotiation(SPIN).

3. Spatial Location Strategy: A third strategy routing found in WSN routing protocols uses the knowledge about the spatial position of sensor nodes to query the WSN in a localized way. If the deployment of sensor nodes is known, queries for data can be directed to the area of interest

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WSN Routing ProtocolsWSN Routing Protocol Types Routing protocols can be classified by several different ways and

considerations , it mat be classified based on “ how and when they acquire routes in the network” to :I. Reactive Protocols, Such as : Ad-hoc On-Demand

Distance Vector (AODV).II. Proactive Protocols, Such as : Optimized Link State

Routing (OLSR).Or may be based on the network structure to :III. Flat-based routing protocols where each node plays the

same role and is typically assigned the same functionality.IV. Hierarchical-based routing protocols(also known as

clustering-based routing protocol) where the nodes have to self-organize themselves into several local clusters, each of which has one node serving as the cluster-head. A cluster-head collects all the messages in that cluster and then forwards an aggregate message to a remote base station (BS). the Low Energy Adaptive Clustering Hierarchy protocol (LEACH) is considered one of the most common protocol in this categorize .

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Energy- Efficient Routing Protocol Algorithms


2. Location based routing protocols It needs some location information of the sensor nodes. Location information can be obtained from GPS (Global Positioning System) signals, received radio signal strength, etc. Using location information, an optimal path can be formed without using flooding techniques.

3. Hierarchical routing protocolsIt is used to perform energy efficient routing, i.e., higher energy nodes can be used to process and send the information; low energy nodes are used to perform the sensing in the area of interest. e.g. LEACH, TEEN, APTEEN. 18

Energy- efficient routing protocol

algorithms

Data centric Location based Hierarchical

1. Data centric protocols it are query based and they depend on the naming of the desired data.

Energy efficient routing algorithm can be categorized as show in the

diagram below :

Energy- Efficient Routing Protocol AlgorithmsIn this presentation we will address to two types of these algorithms1. LEACH (Low Energy Adaptive Clustering Hierarchy)It is hierarchical clustering algorithm which arranges the nodes in the network into small clusters and chooses one of them as the cluster-head. Node first senses its target and then sends the relevant information to its cluster-head. Then the cluster head aggregates and compresses the information received from all the nodes and sends it to the base station.Because The nodes chosen as the cluster head drain out more energy as compared to the other nodes as it is required to send data to the base station which may be far located.

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So, LEACH uses random rotation of the nodes required to be the cluster-heads to evenly distribute energy consumption in the networkIts operations can be divided into two phases:-i. Setup phase .ii. Steady phase .

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LEACH ‘s phases algorithms

Steady phase Set up phase


Energy- Efficient Routing Protocol Algorithms DECSA (Distance-Energy Cluster Structure Algorithm)It is hierarchical routing algorithm based on the same concepts of the classic clustering routing algorithm LEACH and it is considered an improved version of LEACH. The WSN structure under this algorithm is divided in three hierarchal level , which divides the nodes into four categories: Base Station(BS) , Base Station Cluster head(BCH), ordinary cluster head node (CH), and common sensor node (SN). As shown in figure below

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The DECSA algorithm is a distributed competitive unequal clustering algorithm, it considers both the distance and residual energy information of nodes.Its operations can be divided into two stages :-i. Initialization stage.ii. Stable working stageAnd to minimize energy consumption,the stable working stage should be greatly longer than the initialization stage.

So if we compare the “LEACH” with “DECSA”We will realize that “LEACH” :1. It does not consider the location of sensor nodes, and the selection of

cluster head nodes is random, causing the uneven distribution of cluster head nodes That is, the cluster-heads can concentrate a specific area within the network.

2. It cannot guarantee a good cluster-head distribution .3. It is not good for unbalanced-energy network and it leads to the early

death of some nodes in this network because it does not consider the residual energy of nodes where its algorithm supposes the initial energy of all nodes are same, and the energy consumption of becoming cluster head node are basically the same in the first cluster head election.

while the “DECSA”4. It improves the process of cluster head selecting and the process of

cluster forming.5. It reduces the adverse effect on the energy consumption of the

cluster head, resulting from the non-uniform distribution of nodes in network

6. It avoided the direct communication between the Base Sensor and cluster head, which has low energy and far away from Base Sensor.

thus it effectively balances the energy consumption and prolongs of the WSN lifetime .

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we addressed the WSN lifetime and we realized that the lifespan of WSN is affected by many reasons such as nodes deployment manner , the energy of transceiver and the amount of overheads signals which are forwarded via network , and we realized the "Energy Hole" problem and we comprehend the solutions of it . and infer that the different data forwarding mechanisms lead to different amount of and different distribution of energy consumption , thus the good choice of routing protocol for the certain types of deployment under particular radio features plays the main role in saving the nodes power , thus maximize of the WSN lifespan and this make the routing protocol is the major engine of the saving energy in the WSN . then we addressed the WSN routing protocol types and understand its mechanisms and its influences on the WSN lifetime , then study the LEACH and DECSA efficient-energy clustering routing algorithms and we concluded the DECSA has a better performance than the original LEACH protocol.

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Conclusion

At the end , I want to thank Associated Prof. Dr. Ali Gökhan Yavuz

for your help and supportAnd say

“ thank you to all attendees “

Teşekkür Ederim

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wireless sensor network lifetime constraints

Engineering