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Routing Protocols for Wireless Sensor Networks


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  • 1. Power Aware Routing protocols In Wireless Sensor Networks BY DARPAN DEKIVADIYA 09BCE008DEPARTMENT OF COMPUTER SCIENCE AND ENGINEERING AHMEDABAD-382481 April 2012
  • 2. Power Aware Routing protocols In Wireless Sensor Networks Seminar Submitted in partial fulfillment of the requirements For the degree of Bachelor of Technology In Computer Engineering By DARPAN DEKIVADIYA 09BCE008DEPARTMENT OF COMPUTER SCIENCE AND ENGINEERING AHMEDABAD-382481 April 2012
  • 3. Certificate This is to certify that the Seminar entitled ”Power Aware Routing protocols in WirelessSensor Networks” submitted by DARPAN DEKIVADIYA(09BCE008), towards the partialfulfillment of the requirements for the degree of Bachelor of Technology in Computer Engi-neering of Nirma University of Science and Technology, Ahmedabad is the record of workcarried out by him under my supervision and guidance. In my opinion, the submitted workhas reached a level required for being accepted for examination. The results embodied inthis Seminar, to the best of my knowledge, haven’t been submitted to any other universityor institution for award of any degree or diploma. Prof. Jitali Patel Prof. D. J. Patel Assistant Professor, Professor and Head, Dept. of Computer Science & Engg., Dept. of Computer Science & Engg., Institute of Technology, Institute of Technology, Nirma University, Ahmedabad Nirma University, AhmedabadProf. Ankit ThakkarGuide and Assistant Professor,Institute of Technology,Nirma University, Ahmedabad iii
  • 4. Abstract iv Recent developments in the area of micro-sensor devices have accelerated advances in thesensor networks field leading to many new protocols specifically designed for wireless sensornetworks (WSNs). Wireless sensor networks with hundreds to thousands of sensor nodescan gather information from an unattended location and transmit the gathered data to aparticular user, depending on the application. These sensor nodes have some constraints dueto their limited energy, storage capacity and computing power. Data are routed from onenode to other using different routing protocols. There are a number of routing protocols forwireless sensor networks. This report gives the brieg idea about Routing Protocols in WirelessSensor Networks which includes Data Dissemination and Data Gathering Protocols.It alsoincludes classification and comaparision of these Routing Protocols. iv
  • 5. Acknowledgements v I would like to express my heartfelt gratitude to Prof.Ankit Thakkar, Professor in De-partment of computer science and engineering for her valuable time and guidance that madethe seminar project work a success. Thanking all my friends and all those who had helpedme in carrying out this work. I am also indebted to the library resources centre and interestservices that enabled us to ponder over the vast subject of ”Power Aware Routing protocolsin Wireless Sensor Networks”. - DARPAN DEKIVADIYA 09BCE008 v
  • 6. ContentsAbstract ivAcknowledgements v1 Introduction to WSN 12 Classification Of Routing Protocols 3 2.1 Based on Mode of Functioning and Type of Target Applications . . . . . . . 3 2.1.1 Proactive :- . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.1.2 Reactive :- . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.1.3 Hybrid :- . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.2 According to the Participation style of the Nodes. . . . . . . . . . . . . . . . 4 2.2.1 Direct Communication :- . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.2.2 Flat :- . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.2.3 Clustering Protocols :- . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.3 Depending on the Network Structure . . . . . . . . . . . . . . . . . . . . . . 5 2.3.1 Data Centric :- . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.3.2 Hierarchical :- . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.3.3 Location Based :- . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 Data Dissemination Protocols 6 3.1 Flooding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 3.2 Gossiping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3.3 Rumor Routing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 3.4 Sequential Assignment Routing :- . . . . . . . . . . . . . . . . . . . . . . . . 9 3.5 Direct Diffusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 3.6 Sensor Protocol for Information via Negotiation . . . . . . . . . . . . . . . . 11 3.7 Geographic Hash Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 Data Gathering Protocols 13 4.1 Direct Transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 4.2 Power Efficient Gathering for Sensor Information Systems . . . . . . . . . . 14 4.3 Binary Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 4.4 Chain Based Three level Scheme . . . . . . . . . . . . . . . . . . . . . . . . . 16 vi
  • 7. Chapter 1Introduction to WSN A wireless sensor network (WSN) consists of spatially distributed autonomous sensorsto monitor physical or environmental conditions, such as temperature, sound, vibration,pressure, motion or pollutants and to cooperatively pass their data through the network toa main location. The more modern networks are bi-directional, also enabling control of sensor activity.The development of wireless sensor networks was motivated by military applications suchas battlefield surveillance; today such networks are used in many industrial and consumerapplications, such as industrial process monitoring and control, machine health monitoring,and so on. Figure 1.1: Typical multi-hop wireless sensor network architecture 1
  • 8. The WSN is built of ”nodes” from a few to several hundreds or even thousands, whereeach node is connected to one (or sometimes several) sensors. Each such sensor network nodehas typically several parts: a radio transceiver with an internal antenna or connection to anexternal antenna, a microcontroller, an electronic circuit for interfacing with the sensors andan energy source, usually a battery or an embedded form of energy harvesting. A sensor node might vary in size from that of a shoebox down to the size of a grainof dust, although functioning ”motes” of genuine microscopic dimensions have yet to becreated. The cost of sensor nodes is similarly variable, ranging from a few to hundreds ofdollars, depending on the complexity of the individual sensor nodes. Size and cost constraintson sensor nodes result in corresponding constraints on resources such as energy, memory,computational speed and communications bandwidth. The topology of the WSNs can vary from a simple star network to an advanced multi-hopwireless mesh network. The propagation technique between the hops of the network can berouting or flooding 2
  • 9. Chapter 2Classification Of Routing Protocols Routing techniques are required for sending data between sensor nodes and the basestations for communication. Different routing protocols are proposed for wireless sensornetwork. These protocols can be classified according to different parameters. ˆ Routing Protocols can be classified as Proactive, Reactive and Hybrid, based on their Mode of Functioning and Type of Target Applications. ˆ Routing protocols can be classified as Direct Communication, Flat and Clustering Protocols, according to the Participation style of the Nodes. ˆ Routing Protocols can be classified as Hierarchical, Data Centric and location based, depending on the Network Structure.2.1 Based on Mode of Functioning and Type of Target Applications2.1.1 Proactive :- In a Proactive Protocol the nodes switch on their sensors and transmitters, sense theenvironment and transmit the data to a BS through the predefined route. e.g. The Low Energy Adaptive Clustering hierarchy protocol (LEACH) utilizes this typeof protocol.2.1.2 Reactive :- if there are sudden changes in the sensed attribute beyond some pre-determined thresholdvalue, the nodes immediately react. This type of protocol is used in time critical applications. e.g. The Threshold sensitive Energy Efficient sensor Network (TEEN) is an example ofa reactive protocol. 3
  • 10. 2.1.3 Hybrid :- Hybrid protocols incorporate both proactive and reactive concepts. They first computeall routes and then improve the routes at the time of routing. e.g. Adaptive Periodic TEEN(APTEEN) is an example of a reactive protocol.2.2 According to the Participation style of the Nodes.2.2.1 Direct Communication :- In this type of protocols, any node can send information to the Base Station(BS) directly.When this is applied in a very large network, the energy of sensor nodes may be drainedquickly. Its scalability is very small. e.g. SPIN is an example of this type of protocol.2.2.2 Flat :- In the case of flat protocols,if any node needs to transmit data, it first searches for a validroute to the BS and then transmits the data. Nodes around the base station may drain theirenergy quickly. Its scalability is average. e.g. Rumor Routing is an example of this type of protocol.2.2.3 Clustering Protocols :- According to the clustering protocol,the total area is divided into numbers of clusters.Each and every cluster has a cluster head (CH) and this cluster head directly communicateswith the BS. All nodes in a cluster send their data to their corresponding CH. e.g. TEEN is an example of this type of protocol. 4
  • 11. 2.3 Depending on the Network Structure2.3.1 Data Centric :- Data centric protocols are query based and they depend on the naming of the desireddata, thus it eliminates much redundant transmissions. The BS sends queries to a certainarea for information and waits for reply from the nodes of that particular region. Since datais requested through queries, attribute based naming is required to specify the properties ofthe data. Depending on the query, sensors collect a particular data from the area of interestand this particular information is only required to transmit to the BS and thus reducing thenumber of transmissions. e.g. SPIN was the first data centric protocol.2.3.2 Hierarchical :- Hierarchical routing is used to perform energy efficient routing, i.e., higher energy nodescan be used to process and send the information; low energy nodes are used to perform thesensing in the area of interest. examples: LEACH, TEEN, APTEEN.2.3.3 Location Based :- Location based routing protocols need some location information of the sensor nodes.Location information can be obtained from GPS (Global Positioning System) signals, re-ceived radio signal strength, etc. Using location information, an optimal path can be formedwithout using flooding techniques. e.g. Geographic and Energy-Aware Routing(GEAR) 5
  • 12. Chapter 3Data Dissemination Protocols Data dissemination is the process by which queries or data are routed in the sensornetwork. The data collected by sensor nodes has to be communicated to the BS or to anyother node interested in the data. The node that generates data is called a source and theinformation to be reported is called an event. Anode which is interested in an event andseeks information about it is called a sink. Traffic Models have been developed for sensornetworks such as the data collection and data dissemination (diffusion) models. In the datacollection model, the source sends the data it collects to a collection entity such as the BS.This could be periodic or on demand. The data is processed in the central collection entity.Data diffusion, on the other hand, consists of a two-step process of interest propagation anddata propagation. an interested is a descriptor for a particular, intrusion or presence of bio-agents. For every event that a sink is interested in , it broadcasts its interest to its neighborsand periodically refreshes its interest. The interest is propagated across the network andevery node maintains an interest cache of all events to be reported.3.1 Flooding In Flooding, Each node Which receives a packet broadcasts it, if the maximum hop countof the packet is not reached and node itself is not the destination of the packet.This techniquedoes not require complex topology maintenance or route discovery algorithms. Flooding has Following disadvantages : ˆ Implosion : This is situation when duplicate messages are sent to the same node. This occurs when a node recieves coppies of the same message from many of its neigh- bours. ˆ Overlap : The same event may be sensed by more than one node due to overlapping of regions of coverage. this results in their neighbors receiving duplicate reports of the same event. ˆ Resource Blindness : The flooding protocol does not consider theavailable energy at the nodes and results in many redundant transmissions. so,it reduces the network lifetime. 6
  • 13. 3.2 Gossiping Gossiping is modified version of flooding, where the nodes do not broadcast apacket, butsend packets to a randomly selected neighbor. This avoids the problem of Implosion. It takes a long time for a message to propogate throughout the network. Though gossipinghas considerably lower overhead than flooding, it does not guarantee that all nodes of thenetwork will recieve the message. It relies on the random neighbor selection to eventuallypropogate the message throughout the network. 7
  • 14. 3.3 Rumor Routing Rumor Routing is an agent based path creation algorithm. Agents are long-lived entitiescreated at random by nodes. These are basically packets which are circulated in the net-work to establish shortest path to events that they encounter.They can also perform pathoptimizations at nodes they visit. When agent finds a node whose path to an event is longerthan its own, it updates the nodes routing table. Figure 3.1: Rumor Routing Figure 3.1 illustrates the working of Rumor Routing algorithm. In figure 3.1(a), the agenthas initially recorded a path distance 2 to event E1. Node A’s table shows that it is at adistance 3 from event E1 and distance 2 from E2. when the agent visits node A, i+t updatesits own path state information to include the path to event E2. The updating is with onehop greater distance than what it found in A, to account for the hop between any neighborof A that the agent will visit next, andA. It also optimizes the path to e1 recorded at nodeA to the shorter path through node B. The updated status of the agent and node table isshown in figure 3.1(b). When a query is generated at a sink, it is sent on a ranom walk with the hope that it willfind a path leading to the required event. This is based on high probability of two straightlines intersecting on a planar graph, assuming the network topology is like a planar graph,and the paths established can be approximated by straight lines owing to high density of thenodes. If a query does not find an event path, the sink times out and usesflooding as lastresort to propagate the query. For instance, as in figure 3.1(c), suppose a query for event E1 is generated by node P.Through a random walk, it reaches A, where it finds the previously established path to E1.Hence, the query is directed to E1 through node B, as indicated by A’s table. 8
  • 15. 3.4 Sequential Assignment Routing :- The Sequential Assignment Routing(SAR) creates multiple trees ,where the root of eachtree is a one hop neighbor of sink.Each tree grows outward from the sink and avoids nodeswith low throughput or high delay. At the end of the procedure, most nodes belong tomultiple trees. An instance of tree formation is illustrated in figure. Figure 3.2: Sequential Assignment Routing The tree rooted at A and B. Two of the one hop neighbors of the sink are shown. NodeC belongs to bothtrees and has path length of 3 and 5 respectively to the sink, using thetwo trees.Each sensor node records two parameters about each path through it: 1. The available energy resources on the path. 2. An additive QoS metric such as delay. 9
  • 16. This allows a node to choose one path from among many to relay its message to thesink.The SAR chooses a path with the high estimated energy resources and provisions can bemade to accomodate packets of different properties.A wieghted QoS metric is used to handleprioritized packets which computed as a product of priority leveland delay.The routing esuresthat the same weighted QoS metric is maintained. Thus, higher priority packets take lower delay paths and lower priority packets have touse the paths of greater delay. e.g. If node C generates a packet of priority 3, it follows thelonger path along tree B, and a packet of priority 5 will follow the shorter path alongtree that the priority X delay QoS metric is maintained. SAR minimizes the average weighted QoS metric over the lifetime of the network. Thesink periodically trigers a metric update to reflectthe changes in available energy resourcesafter some transmissions.3.5 Direct Diffusion This potocol is useful in scenario where the sensor nodes themselves generate requests/queriesfor data sensed by other nodes, instead of all queries arising only from a BS. Hence the sinkfor the query could be a BS or a sensor node. The direct diffusion routing protocol improveson data diffusion using interest gradients. Each sensor node names its data with one or moreattributes and other nodes express their interest depending on these attributes. Attributevalue pairs can be used to describe an interest in intrusion data as follows. The sink has to periodically refresh its interest if it still requires the data to be reportedit. Data is propagated along the reverse path of the interest propagation. Each path isassociated with a gradient that is formed at the time of interest propagation. Each pathis associated with the gradient that is formed at the time of interest propagation. Whilethe positive gradients encourage the data flow along the path, Negative gradients inhibitthe distribution of data along a perticular path. The strength of the interest is differenttoward different neighbors, resulting into source to sink paths with different gradients. Thegradient coresponding to an interest is derived from the interval/data-rate field specified inthe interest. This model uses data naming by attributes and local data transformation to reflect thedata centric nature of sensor network operations. The local operations of Data agreegationare application-specific gradient model. The network wide results of local interaction byregulating the flow of data along different paths depending on the expressed interest. 10
  • 17. 3.6 Sensor Protocol for Information via Negotiation family of protocols for information via negotiation (SPIN) is proposed in [5]. SPIN usesnegotiation and resources and adaption to address the deficiencies of flooding. Negotiationreduces overlap and implosion, and a threshold based resource-aware operation is used toprolong network lifetime. Meta-data, or data describing data, is transmitted instead of rowdata. This requires fewer bytes and can be in an application-specific format. SPIN has three types of messages: ADV,REQ, and DATA. A sensor node broadcasts anADV containing meta-data describing actual data. If a neighbor is interested in the data ,it sends REQ for the data. Then the sensor node sends the actual DATA to the neighbor.The neighbor again sends ADVs to its neighbors and this process continues to disseminatethe data throughout the network. the simple version is shown in figure. Figure 3.3: Sensor Protocol for Information via Negotiation SPIN is based on data-centric routing, where the nodes advertise the available datathrough an ADV and wait for requests from interested nodes. SPIN-2 expands on SPIN,using an energy or resource threshold to reduce participation. A node may participate inthe ADV-REQ-DATA handshake only if it has sufficient resources above a threshold. 11
  • 18. 3.7 Geographic Hash Table Geographic Hash Table is a system based on data centric storage inspired by internetscale distributed hash table systems such as chard and Tapestry, GHT hashes keys intogeographic co-ordinates and stores a pair at the sensor node nearest to the hash value. Thecalculated hash value is mapped onto a unique node consistently, so that queries for the datacan be routed to the correct node. Stored data is replicated to ensure redundancy in case ofnode failures and consistently protocol is used to maintain the replicated data. The data isdistributed among nodes such that it is scalable and the storage load is balanced. GHT is more effective in large network where a large number of events are detected butnot all are queried. In this case data observed is stored in a distributed manner acrossall nodes, instead of being routed to central external storage. Queries are routed to thenearest node which contains a copy of the relevant data. This makes the storage and trafficdistribution uniform. 12
  • 19. Chapter 4Data Gathering Protocols The objective of the data-gathering problem is to transmit the sensed data from eachsensor node to a BS. One round is defined as the BS collecting data from all the sensor nodesonce. The goal of algorithms which implement data gathering is to maximize the number ofrounds of communication before the nodes die and the network becomes inoperable. Thismeans minimum energy should be consumed and the transmission should occur with mini-mum delays, which are conflicting requirements. Hence, the energy X delay metric is used tocompare algorithms, since this metric measures speedy and energy-efficient data gathering.A few algorithms that implement data gathering are discussed below.4.1 Direct Transmission All sensor nodes transmit their data directly to BS. This is extremely expensive in termsof energy consumed, since the BS may be very far away from some nodes. Also, nodes musttake turns while transmitting to the BS to avoid collision , so the media access delay is alsolarge. Hence, this scheme performs poorly with respect to the energy X delay matrix. 13
  • 20. 4.2 Power Efficient Gathering for Sensor Information Systems Power Efficient Gathering for Sensor Information Systems (PEGASIS) is a data-gatheringprotocol based on the assumption that all sensor nodes know the location of every other node,that is, the topology information is available to all nodes. Also,any node has the requiredtransmission range to reach the BS in one-hop, when it is select as a leader. The goals ofPEGASIS are as follows : ˆ Minimize the distance over which each node transmits. ˆ Minimize the broadcasting overhead. ˆ Minimize the number of messages that need to be sent to the BS. ˆ Distribute the energy consumption equally across all nodes. 14
  • 21. Figure 4.1: Sequential Assignment Routing A greedy algorithm is used to construct a chain of sensor nodes, starting from the nodefarthest from the BS. At each step, the nearest neighbor which has not been visited is addedto the chain. The chain is constructed a priory, before data transmission begins and isreconstructed when nodes die out. At every node, data fussion is carried out. so, that onlyone message is passed on from one node to next. A node which is designated as the leaderfinally transmits one message to BS. Leadership is transffered in sequential order and a token is passed. so that the nodesknow in which direction to pass messages in order to reach the leader. A possible chainformation is illustrated in figure. The delay involved in message reaching the BS is O(N),where N is the total number of nodes in the network. 15
  • 22. 4.3 Binary Scheme This is also a chain-based scheme like PEGASIS, which classifies nodes into differentlevels. All nodes which recieve messages at one level rises to the next level. Step 1 :- S0 → S1 S2 → S3 S4 → S5 S6 → S7 Step 2 :- S1 → S3 S5 → S7 Step 3 :- S3 → S7 Step 4 :- S7 → BS The number of nodes is halved from one level to the next. For instance,consider a networkwith eight nodes labled from S0 to S7. In figure agreegated data reaches the BS in 4 stepswhich is O(log2 N ).where N is the number of nodes in the network.4.4 Chain Based Three level Scheme For non CDMA sensor nodes, a binary scheme is not applicable. The chain based threelevel scheme addresses this situation. In this scheme chain is constructed as in PEGASIS.The chain is devided into into number of groups to space out simulteneous transmission inorder to minimize interference. Within a group , nodes transmit one at a time. One node out of each group agreegates data from all group members and rises to thenext level. The index of this leader node is decided priori. In the second level all nodes aredevided into two groups and the third level consist of a message exchange between one nodefrom each group of second level. Finally the leader transmits a single message to BS. Step 1 :- S0 → S1....S6 → S7 ← S8 ← S9 S10 → S11....S16 → S17 ← S18..........S97 ←S98 ← S99 Step 2 :- S7 → S17 ← S27 ← S37 ← S47 S57 → S67 ← S77 ← S87 ← S97 Step 3 :- S17 ← S67 Step 4 :- S67 → BS The working of this scheme is explain in above figure.Suppose Network has 100 nodesand the group size is 10 for the first level and 5 for second level. Three levels have beenfound to give the optimal energy X delay through simulation. 16
  • 23. References :-ˆ Ad Hoc Wireless Networks By,C.Shiva Ram Murthy and B.S.Manojˆˆ sensor network 17