I. INTRODUCTION:WirelessSensor Networks (WSN) provides a new model of sensing and dispersinginformation from various environments, aiming to serve the differentapplications. These networks are recognized as the most fundamental advancementof the century and are the outcome of recent advances in electronic sensors,communication technologies, and computation algorithms. WirelessSensor Networks comprise of a vast number of autonomous, sensing, computing,and communicating elements that gives user or administrator the ability toinstrument, observe and react to events and phenomenon in a particularenvironment 1. The wireless nodes encapsulate the embedded electronic sensorsalong with the battery and RF devices. The sensors will sense and recognizemany different biological parameters like temperature, pressure, pollution,etc., communicate the gathered data with the neighboring nodes and ultimatelycompute the data to get the results.
So application space of Wireless SensorNetworks is huge as they can be deployed in various fields like agriculturemonitoring, smart homes, healthcare, target tracking, military surveillance,earthquake observation, etc. In spite of the numerous applications, WSN posessome limitations which are constrained energy supply, restricted computationand communication abilities.A wireless sensor network includes thousands of sensor nodes which aredensely deployed in an unattended environment possessing the sensingcapabilities, wireless communications, and computations. Wireless communicationand MEMS are the two advances which have contributed profoundly to thedevelopment of wireless sensor network. These systems contain sensor nodes thatcollect, process, store and transfer information fromone node to another. Sothe data can be processed as it passes the network.
Wireless Networks are of 2 types:a) Infrastructure network.b) Ad-hoc network.Infrastructurenetwork encompasses fixed and wired gateways. A mobile host interacts withbridge in the network within its radius.
When it goes out of range from onebase station, it unites with the new base station within radius and startscommunicating with it. This whole process is termed as handoff. Whereas, Ad-hocnetwork is a group of wireless mobile nodes which interacts with each other anddo not require any fixed network infrastructure such as base station or accesspoint and can be quickly set up as needed.Network Architecture: The block diagram of a wireless sensor network ispresented in fig1.1.Main components of WSN are:a) Processing Unit.
b) Power Supply.c) Sensing Unit.d) Communication /TransceiverUnit.e) Software part. Fig 1 Components of Sensor Nodesa) ProcessingUnit – It collects data from various sources, processes the data and thenstores it.
The cpu of the sensor node decides computational capabilities andenergy consumption by the sensor node.b) Power Unit– Life span of the sensor node is dependent on the battery of the system. Powerunit is responsible for providing long life, has the ability to recharge underlow current, and has low self-discharge. c) SensingUnit – A sensor is a gadget which senses the physical sensation for e.g.
velocity, weight, etc. and changes it into analog signal. Now analog to digitalconversion takes place.
WSN has large number of sensor nodes. Each nodecontains more than one sensor. The different types of sensors available are -magnetic field sensor, acoustic sensor, temperature sensor, acoustic sensor,magnetic field sensor etc. d) Communication /Transceiver Unit – This unit has circuits of bothtransmitter and receiver, on the single board. The unit receives command fromprocessing unit and passes it to the another nearby nodes in the network. Thereare three types of communication-• OpticalCommunication – In this type of communication, transmitter converts a signalinto optical form at the sender’s end. This optical signal is then sent to thereceiver’s end and is converted back into original signal at receiver’s end.
• Infrared Communication – This isan Omni-directional communication within plane which has a short range of about1m and has no antenna.• Radio-frequency (RF) – As Radio has four operating modes (transmit,receive, idle, sleep), it plays a significant role in power consumption. It isbased on electromagnetic waves.e) Software – It provides services such as – • Sensor manager – provides the access to sensors inthe network and manage the delivery of sensor data.
• Storage – provides the persistent storage of datastreams.• Query manager – performs query processing andmanages active queries.• Integrityservices are used for access control. WSN Routing –The process of moving a packet of data from source to destination in a networkis called routing. There are two main activities in routing:a) findingoptimal path and b) transferringpacket through internetwork.
In multi-hopnetworks, the data packet from the source node cannot reach the destinationnode directly. So, here intermediate sensor nodes comes into play. They have torelay their packets. Routing tables contains the list of nodes for any givenpacket destination.Routing can beStatic or Dynamic. Static routing strategy is stated statically in the routerand a routing table is maintained whereas dynamic routing depends on the stateof the network.
Challenges inWireless Sensor Networks – a) Because of large number of sensor nodes in the network, it is notpossible to build global addressing scheme for their deployment. b) Almost all the applications of sensor networks require the flow ofsensed data from the multiple sources to a particular base station.c) Nodes in the network have limited energy, processingand storage capacities, hence require careful management of resources. II. ALGORITHM USEDAnt ColonyOptimization (ACO)ACO algorithmis based on the real ant’s food finding behavior by taking the shortest routefrom the ant colony to the food source. It is observed that ants while searchingfor the food release a certain amount of pheromone in their way.
Whilereturning home, the ants follow the same path marked by the pheromone depositedearlier and again deposit the pheromone on the way back. In this way, all theants follow the same path and are expected to return earlier as amount ofpheromone deposit increases in shorter path than the ants following a longerpath. ACO takes motivation from the behavior of the ants. The ants depositpheromone trail on the round trip in order to mark a path that should befollowed by other members of the ant colony. The pheromone deposit keep onincreasing on the path frequently visited by the ants whereas the paths rarelyvisited by the ants are lost due to lack of pheromone deposit as a fact thatthe pheromone vanishes after a certain interval of time.
ACO in Network RoutingSI emerges asoverall intellect of groups of simple agents. This approach gives importance todistributedness, flexibility, robustness and direct or indirect communication amongthe relatively simple agents 2. The agents are autonomous entities and havethe capability to adapt, cooperate and move intelligently from one location tothe other in the communication network.
There are two types of ant agents:FANT- Forward Ants and BANT- Backward Ants. Both the ants perform differentfunctioning. BANTs utilize the information gathered by the FANTs on their triptime from source to destination. The purpose of FANTs is to report networkdelays to BANTs.
In a network routing problem, a setof packets are routed from a source to the destination. The agents pass theinformation as:1. Each network node releases FANT toall other nearby nodes at regular time interval.2. Ants find a path to destinationrandomly based on current routing tables.
3. The FANT creates a stack and pushin trip times for every node as that node has reached.4. When the destination is reached,the BANT inherit the stack.5.
The BANT pop the stack entries andfollows the path in reverse.6. The routing table of each visitednodes are updated based on trip times.There are three phases in ACO:· Route Discovery phase- This phaseuses two ant agents: Forward Ant (FA) and Backward Ant (BA). Control packets areused to discover a route from source to destination. The control packets aremobile agents who establish routes between nodes while roaming in the network.
· Route Maintenance phase- As networkkeeps on changing frequently; a route found good during discovery phase mayturn bad due to some constraints such as congestion, signal strength, etc.,Route Maintenance is quite important in WSN’s.· Route Failure handling- It isresponsible for generating alternative routes in case of any failure.III.
LITERATURE SURVEYThe collectivebehavior of biological species such as ants have been studied by theresearchers. A number of routing protocols have already been proposed. Most ofthem are based on the Ant Colony Optimization (ACO) which is to solve thecomputational problems based on probability techniques.
AdamuMurtalaZungeruet.al, (2013), in their paper “EnergyEfficiency Performance Improvements for Ant-Based Routing Algorithm in WirelessSensor Networks” depicts three changesto the EEABR calculation to further enhance its energy proficiency. The changesto the first EEABR are based on mostly three aspects- another plan to keenlyintroduce the routing tables givingpriority to neighboring nodes that simultaneously could be the destination,intelligent update of routing tables in case of a node or link failure, andreducing the flooding ability of ants for congestion control.K.
Sayed AliFathimaet. al, (2013), in their paper “Ant Colony Optimization based Routing inWireless Sensor Networks” presented a new technique called Bio-Inspiredmechanism has been proposed for routing. ACO is a dynamic and Bio-Inspired reliableprotocol. It reduces the energy consumption and optimizes the routing path,providing an effective multi-path data transmission.
Anjali et. al,(2013), in their paper , “Routing based Ant Colony Optimization in WirelessSensor Networks” proposed a way to reduce the energy consumption inWireless sensor networks routing process using Ant Colony Optimization.FatemehRismanianYazdi (2013), in her paper “Ant Colony With ColoredPheromones Routing For Multi Objectives Quality Of Services In Wireless SensorNetworks” discovers a new Ant-routing algorithm with colored pheromones andclustering techniques for satisfying users’ Quality of Service (QoS)requirements in Wireless Sensor Networks. The proposed algorithm takes in toaccount the traffic diversity, and provides a different routing using variousQoS metrics. Nabil Ali Alrajehet. al, (2013), in their paper, “Secure Ant-Based RoutingProtocol for Wireless Sensor Network” presented that an adaptive secure routingprotocol which is based on bio-inspired mechanism. It uses distributedant-based methodology to select two optimal paths keeping in view routesecurity.