Data Gathering And Dissemination In Wireless

Data Gathering And Dissemination In radio setA radiocommunication demodulator vane is special kind of ad hoc mesh topologys that consists of a number of low-cost, low-power, and multi-functional wireless detector inspissations, with sensing, wireless communications and com contriveation capabilities 1,2,3. These sensor nodes communicate over a neat range via a wireless medium and collaborate to accomplish a common task, like environmental monitoring, military surveillance, and industrial process control 3. Wireless sensor networks bring forth open up for wise opportunities to observe and interact with the physical environment around us. They enable us now to collect and cooperate data that was difficult or impossible before 4. Although Wireless Sensor Networks have given new ways to provide information from variety of activitys, no matter of the nature of physical environment, it is seen as a ch onlyenging task to extract data from sensor network. Data dissemination and realiseing atomic number 18 two toll used in sensor networks to describe two categories of data handling regularitys. Data dissemination is a process by which data and queries for data be r come forthed in the sensor networks where as data gathering is to transmit data that has been peaceful by the sensor nodes to the base stations. Data gathering protocols aim to diminish the energy consumption and detention of data gathering process 5. Although there be differences among these two but almost all(a) the literature called in concert as r erupting protocols. Unlike traditional wireless communications networks such as mobile ad hoc and cellular systems, wireless sensor networks have the following peculiar characteristics and constraints 3 high density sensor node deployment, battery or no power sensor nodes, low memory and processor capacity, self-configurable, unreliable sensor nodes, data redundancy, application specific and dynamic topology. Due to above characteristics and constraints of wireless sensor networks, the extraction of data from the network is always a challenge. Therefore, it is important that the design of protocols for data gathering and dissemination takes c atomic number 18 about these challenges. The main design challenges of routing protocols for wireless sensor network are Energy, Processing power and Memory. Some of the design challenges as reflected in 3, 6 are highlighted belowLarge number of sensor nodes Since most of the wireless sensor networks composed of large sensor nodes, it is very difficult to have an addressing scheme like other wireless networks. The traditional IP scheme is non feasible to apply for wireless sensor networks. Moreover, the sensor nodes are deployed at random in hostile environment.Limited energy capacity The sensor nodes are battery powered, so they have limited energy. This is the main challenges in purpose wireless sensor networks. In practice, sensor network deployment makes sense only if th ey dismiss run unattended for months and years without running short of energy 4. draw of Data Almost all the applications of sensor network require the sensory data from multiple sources to flow towards a single destination node called drop in contrast to the traditional networks.Sensor node billets Most of the proposed routing protocols assumed that the sensor nodes are equipped with global positioning system (GPS), but in practice it is very difficult to manage the locations of sensor nodes. It has become more challenging as sensor networks topology changes frequently due to node failures, miserable from the coverage area.Data redundancy Data collected by various sensor nodes are typically based on common phenomenon hence the chance of data redundancy is very high. The routing protocol needs to incorporate data compendium techniques to decrease the number of transmission.Application Specific The sensor networks are application specific. The requirement of routing protocol changes as per the specific application. It is very challenging to design routing protocols which can meet the requirements of all applications.Scalability The size of the network grows, so the routing protocols need to be scalable to support the addition of sensor nodes. All sensors may not necessarily have resembling capabilities of energy, processing, sensing and communications. These should be taken care term designing the routing protocols.Addition to the above parameters the designing of routing protocols for wireless sensor networks also need to look into following points 6 Node deploymentRelated workSince wireless sensor networks gain its usage in various application areas, there is a growing sideline in this field leading towards continual emergence of new architectural techniques. Wireless sensor network is widely considered as cardinal of the most important technologies of the 21st century 8. In this section we bring out and highlight how our survey differs from the same surveys d bingle previously in this area. We also highlight the scope and target group who volition benefit from our work.In 2, similar survey was carried out on routing protocols for wireless networks. The information in 2 was published or so five years back and many new protocols have not covered. In 3, although it has covered almost all the routing protocols for wireless sensor networks but it does not provide insight knowledge about the protocols. The survey is good for readers provoke in broad area. The goal of 8 is to give a comprehensive survey on routing techniques focvictimization on mobility issues in sensor networks and does not cover all the routing protocols in wireless sensor networks. In this survey, we bring out the comparative study among wireless sensor network routing protocols bringing their differences and similarities. We also bring out the advantages and disadvantages of different protocols to use in different applications of wireless sensor networks. This survey would be useful for both introductory readers as well as for hopeful researchers who would like to get the comprehensive idea about the current-state-of-art regarding the techniques of data gathering and dissemination in wireless sensor networks. However, we follow 3 in classifying the routing protocols into different categories although we put nigh additional protocols which are not covered by 3. We also excluded multi means-based protocol category since it falls under data-centric category. Table 1 shows the different categories of wireless sensor network routing protocols inspired by 3. The representative protocols with (*) marks are our additions.Table 1 Routing Protocols for WSNsCategory of ProtocolsRepresentative ProtocolLocation-based ProtocolsMECN, SMECN,GAF, GEAR, Span, TBF, BVGF, GeRaFData-centric ProtocolsSPIN, Directed Diffusion, record Routing, COUGAR, EAD, ACQUIRE, knowledge-Directed Routing, Gradient-based Routing, Energy-aware routing, Information Dir ected Routing, Quorum-based Information dissemination, Home Agent-based Information Dissemination, *Flooding, *Gossiping.Hierarchical-based ProtocolsLEACH, PEGASIS, HEED, TEEN, APTEENMobility-based ProtocolsSEAD, TTDD, Joint mobility and routing, Data MULES, Dynamic Proxy Tree-based Data Dissemination, *MDCHeterogeneity-based ProtocolsIDSQ,CADR,CHRQoS-based ProtocolsSAR, SPEED, Energy-Aware Routing.Data-Centric ProtocolsThe protocols are differentiated into two categories called data-centric and address-centric. The address-centric routing protocols find the shortest path between source and the destination with addressing scheme like IP whereas in data-centric routing protocols focus is made to search routes from multiple source nodes to a single destination node. In the sensor networks, data-centric routing is preferred where data consolidation and assembling is done by the intermediate nodes on the data coming from multiple sources before sending to the send away node. This way, it saves some energy preventing redundant data transmissions. In this section, we highlight some of the samples of data-centric routing protocols proposed for wireless sensor networks.FloodingFlooding 5 is a data dissemination method where some(prenominal)ly sensor node that receives a packet broadcasts it to its neighboring nodes assuming that node itself is not the destination of the packet. This process continues until the packet arrives the destination or the maximal hop counts for that packet is reached. Flooding though is a simple and easy to implement, but it has problem like implosion (duplicate heart and soul sent to the same node) and overlap (duplicate message receive by the same node) 2. Figure 1 and 2 reproduced from 2 shows the implosion and overlap problems in flooding.GossipingGossiping 5 is based on flooding, but nodes that receives the packet forrad it only to a single randomly selected neighbor. It avoids implosion problem of flooding and it does not waste as much network resources as flooding. However, gossiping is not a reliable data dissemination method since the neighbor node is selected at random, some nodes may not receive that message at all. Moreover, it introduces a delay in propagation of data through the nodes 2 since all the nodes which forwards or sends data need to select a node.SPINSensor Protocols for Information via talks (SPIN) 9, 10 aims to improve the implosion and overlapping problems of classic flooding protocol. The SPIN protocols are based on two key mechanisms namely negotiation and resource adaptation 3. It uses trio types of messages 5 ADV, REQ, and DATA. The sensor node which has collected data sends an ADV message using high-level descriptors or meta-data regarding the actual data. The actual data is transmitted only when the REQ message is standard from the interested nodes. This negotiation mechanism avoids the overlapping and implosion problems of classic flooding because the REQ message is sent from t he interested node only when it does not have that data. Fig. 3, redrawn from 5 shows how these three messages are exchanged and fig. 4 inspired by 9 and reproduced from 11 shows more detail process who SPIN works.There are about four versions of SPIN protocols 6, 9, 10. They are SPIN-PP, SPIN-BC, SPIN-EC and SPIN-RL. both SIPN-PP and SPIN-BC works under ideal condition when energy is not constraint and packet are never lost. SPIN-PP tackles the data dissemination problem by using point to point media where as SPIN-BC uses broadcast media. There other two protocols are the modified versions of SPIN-PP and SPIN-BC in order to network which are not ideal. SPIN-EC is actually SPIN-PP with additional energy conservation capability. Under SPIN-EC, the nodes participate in data dissemination only when it computes that it has enough energy. If the node has plentiful energy, it works as same as SPIN-PP with 3-stage handshake. SPIN-RL is a version of SPIN-BC which tries to recover from the losses in the network by selectively retransmitting the messages.In SPIN topological changes are localized as each node needs to have information of their next immediate one-hop neighbor only. But this type of protocol cannot be used in applications where reliability is of great concern like forest fire and intrusion detection since it does not guarantee the data delivery 2. If the nodes that are interested in data are located far way and the intermediate nodes are not interested then the ADV message will not stock which in turn will not able to get data.Directed DiffusionDirected Diffusion 12 consists of elements like interests, data, messages, gradients and reinforcements. The main objective of the protocol is to use naming scheme to mow the energy usage by avoiding unnecessary routing operations. Interest is a query or interrogation on what user wants and it contains descriptions of a sensing task. Data is the collected or processed information of a physical phenomenon which is named using attribute-value pair. Gradient is a link a neighbor from which interest was received, and it is characterized by data rate, duration, and achievement beat which has derived from the received interest filed 2. A node, usually sink will be broadcasting interest to request data by diffusing interest through its neighbors. The interests are periodically refreshed by the sink. When this interest is received by the intermediate nodes, they cache for future use, or do in-network data aggregation or direct interest based on previous cached data. The source node sends the data back through the reverse path of the interest. When data is received by the nodes, they try to compare with the interest cache before. The data which matches the interest is drawn and then sent via the same path where the interest has received. Out of several paths between sink and the source, one path is selected by network by reinforcement. Once this path is selected, the sink sends the original intere st again with smaller time interval so as to make the source node on the selected path to send data more frequently.Although directed diffusion has advantages that the protocol can in-network data aggregation and caching which saves energy but this protocol cannot not be applicable to all the applications of wireless sensor networks. The protocol can only be applied to such application which is query driven. It is not suitable for the applications such as forest fire detection or intrusion detection. Fig. 4, copied from 12 shows the working of the protocol.Rumor RoutingRumor routing 13 another variation of Directed Diffusion aims to direct the query to the nodes which have observed event rather than flooding the entire network 2. It is a logical compromise between query flooding and event flooding 3. This protocol is only useful if the number of queries compared to number of events is between the two fundamental interaction points. See fig. 5, redrawn from 13.Rumor routing algorithm s introduces an divisor, a long live packet. An agent, which also contains an event table like nodes, travels the network propagating information about local event to the nonadjacent nodes. The agent informs the nodes it encounters of any events it has observed on its way and at the same time it will synchronize its event table with the event table of encountered node. An agent will travel the network for certain number of hops and then die. All the nodes including an agent maintains an event table list that has event-distance pairs, as shown in fig. 6, copied from 13. So when a node generates a query for an event, the nodes that knows the route, can respond to the query by referring its event table 2. In this way, flooding the whole network is avoided. directing rumor routing is proposed in 14, which try to improve latency and energy consumption by considering query and event propagation in straight line or else of random walk in normal rumor routing.CougarCougar 15, 16 is a da tabase approach for tasking sensor networks through declarative queries. Since in-network counting is much cheaper than transmission and communication between nodes, cougar approach proposes a loosely-coupled distributed architecture to support both aggregation and in-network computation. This helps in reducing energy consumption thereby increase lifetime. The architecture introduces a query proxy layer in each sensor node which interacts both with network layer and application layers. The gateway node (where query optimizer is located) generates a query processing plan after receiving queries from the sensor nodes. This query plan specifies both data flow between sensor nodes and in-network computation plan at each individual sensor node. The query plan also contains how to select a leader for the query. The query plan can be viewed at non-leader node and at the leader node. Fig. 7 and fig. 8, redrawn from 15, show query plan at non-leader node (source sensor) and leader node resp ectively.Although, cougar provides solution to interact with the sensor nodes independent from the network layer, but the insertion of proxy layer at each sensor node introduce extra overhead for sensor node in terms of memory and energy consumption 2. Additional delay may be incurred with the relay trying to wait for the packets from other nodes for aggregation before sending to the leader node.ACQUIREACQUIRE 16 is a data-centric routing protocol aiming at large distributed databases. It aims at complex queries which comprise of several sub-queries that are unite by conjunctions or disjunctions in an arbitrary manner. The protocol sends an active query packet into the network. This active query packet is sent by the sink, which takes random path or path predefined or guided. The node which receives this active query packet uses information stored within them to partially resolve the query. If the nodes do not have updated information, they gather the information from their neighbor ing nodes with the distance of d (look-ahead parameter) hops. When the active query is resolved completely, the response is sent back to the node which has issued the query. Some of the assumptions made in this protocol are 17 the sensors, with same transmission range are laid out uniformly in a region and they are stationary and do not fail.EAD Energy-Aware Data-Centric RoutingEnergy-Aware Data-Centric (EAD) 18 aims to construct a virtual book binding containing all active sensors, which is responsible for in-network data processing and relaying traffic. The radios of other nodes which are not in the virtual backbone are put off to conserve the energy. The sensor network is represented by a broadcast tree rooted at the gateway and spanning all the sensors with large leaf nodes. In order to conserve power, the radios of these leaf nodes are put off while the nodes which are in virtual backbone are active for traffic relaying. The protocol tries to construct broadcast spanning tree network with maximum leaf nodes so that maximum energy can be conserved. The model of EAD is to include the neighboring broadcast scheduling and the distributed competition among neighbors, based on residual energy 18. The efficiency of the protocol would be more when the size of the network is small. When the size of the network is large, execution time will be more since the execution process propagates from the sink to the whole network. Other protocol like the one proposed by Shah and Rabaey in 19 also aims at increasing network life time. They use network survivability as the main metric and propose to choose one of the multiple paths with a certain probability so that the whole network life time increases. But the protocol assumes that each node is addressable with some addressing schemes.Information-Directed RoutingLocation-based ProtocolsSince sensor nodes have limited energy capacity, most of the routing protocols aim to slim the consumption of energy in routing processes . In most of the protocols location of the sensor nodes are used to find the distance between two communicating pairs in order to find the best possible path with low energy usage. If location of a particular sensor node is known, query can be sent to that particular location only without sending to other regions which will reduce the number of transmission significantly 2. Location-based protocol makes use of the position information to relay data to the network rather than the whole network. In this section, we describe some of the location-based routing protocols proposed for wireless sensor networks.Minimum Energy Communication Network (MECN)Hierarchical-based Protocols