The underwatermobilead-hocnetworks comprise sensor nodes that are source nodes for gathering underwater-related data. Relay nodes are the mobile nodes for collecting data from sensor nodes and achieving intermittent connectivity among source and destination nodes. Developing an efficient routing protocol for underwater communication is a challenging issue due to limitations of the underwater environment. Underwatermobilead-hocnetworks are intermittent networks where end- to-end path does not exist from source to destination. To overcome these problems a delay and disruption tolerant network (DTN) is a good solution. In the current paper, we consider the Spray and Wait (SaW) routingtechnique. In SaW, source and relay nodes represents the moving nodes, and they try to send data to destination nodes. Based on this, we propose the replica based underwater SaW (USaW) routing for underwatermobilead-hocnetworks. In USaW, source nodes are fixed to the bottom of the surface. Underwater sensor nodes replicate sensor data and provide maximum copies of data to the relay nodes that they encounter. In generally, relay nodes have high capability of transmitting data as compared to sensor nodes in an underwater environment. We analyze the performance of USaW with respect to delivery ratio, network throughput, energy consumption, end-to-end delay, and packet drop rate comparing with existing SaW and prophet routing protocols. [Keywords: USaW; DTN; ad-hoc network; sensor node; routing]
route table are checked to ensure whether there is a current route to that destination node or not. If it is there, the data packet is forwarded to the appropriate next hop toward the destination. If it is not there, the route discovery process is initiated. AODV initiates a route discovery process using Route Request (RREQ) and Route Reply (RREP). The source node will create a RREQ packet containing its IP address, its current sequence number, the destination’s IP address, the destination’s last sequence number and broadcast ID. The broadcast ID is incremented each time the source node initiates RREQ. Basically, the sequence numbers are used to determine the timeliness of each data packet and the broadcast ID & the IP address together form a unique identifier for RREQ so as to uniquely identify each request. The requests are sent using RREQ message and the information in connection with creation of a route is sent back in RREP message. The source node broadcasts the RREQ packet to its neighbours and then sets a timer to wait for a reply. To process the RREQ, the node sets up a reverse route entry for the source node in its route table. This helps to know how to forward a RREP to the source. Basically a lifetime is associated with the reverse route entry and if this entry is not used within this lifetime, the route information is deleted. If the RREQ is lost during transmission, the source node is allowed to broadcast again using route discovery mechanism.
Vishnu Sharma, working as a faculty in CSE Dept. Of Jaypee University of Engg and Technology and presently, he is a Ph.D Candidate at M.P.Technical University, He has about 13 years of teaching experience. He has published more than fifteen papers in the area of MobileAd-hocNetworks & Mobile Computing at National/International Level. He has published the books on Mobile Computing and Advanced Mobile Computing in UPTU, Lucknow (UP) and IP University, New Delhi. He is a life time member of International Association of Computer Science and Information Technology (IACSIT), Singapore and member of CSI. His area of interest includes Mobile Computing, Computer Networks and Communication Technologies, Cryptography and Network Security.
A simple mechanism proposed to prevent the flooding attack in the AODV protocol . In this approach, each node monitors and calculates the rate of its neighbors’ RREQ. If the RREQ rate of any neighbor exceeds the predefined threshold, the node records the ID of this neighbor in a blacklist. Then, the node drops any future RREQs from nodes that are listed in the blacklist. The limitation of this approach is that it cannot prevent against the flooding attack in which the flooding rate is below the threshold. Another drawback of this approach is that if a malicious node impersonates the ID of a legitimate node and broadcasts a large number of RREQs, other nodes might put the ID of this legitimate node on the blacklist by mistake. In , the authors show that a flooding attack can decrease throughput by 84 percent. The authors proposed an adaptive technique to mitigate the effect of a flooding attack in the AODV protocol. This technique is based on statistical analysis to detect malicious RREQ floods and avoid the forwarding of such packets. Similar to , in this approach, each node monitors the RREQ it receives and maintains a count of RREQs received from each sender during the preset time period. The RREQs from a sender whose RREQ rate is above the threshold will be dropped without forwarding. Unlike the method proposed in , where the threshold is set to be fixed, this approach determines the threshold based on a statistical analysis of RREQs. The key advantage of this approach is that it can reduce the impact of the attack for varying flooding rates.
S.Singh and C.S.Raghavendra  projected energy efficiency technique which is achieved by using two separate channels, one for control and other for data. RTS/CTS signals are transmitted over the control channel while data are transmitted over data channel. Nodes with packet to transmit sends a RTS over the control channel, and waits for CTS, if no CTS they receives within a specific time then node enters to a backoff state. However, if CTS is received, then the node transmits the data packet over the data channel. The receiving node transmits a busy tone over the control channel for its neighbours indicating that its data channel is busy. The use of control channel allows nodes to determine when and how long to power off. The length of power off time is determined by different condition. After waking up, a node access the channel over the data channel and found multiple transmission going on. The node uses a probe protocol in this case to find how much time it will power off. Simulation results shows that good range of power saving is achieved.
Like the AOMDV protocol, if an intermediate node finds a problem in the link to the next node while sending data packets to the receiver node and if the number of hops to the receiver node is small, then the node will start a repair process by broadcasting RREQ packets to the receiver node and wait to hear a reply from the receiver node for a period of time called RRE- P_RAIT_TIME. If the node receives a RRREQ from the receiver node, it sends data packets directly through the new path, otherwise it sends route error packets (RERR) through reverse path to the sender node. The sender node removes the invalid path and checks its routing table for an alternative path and sends data packets. Although the routing table of the sender node has alternative paths not used yet, if the sender node receives a new RRREQ packet from the receiver node, it will delete all old paths and update the routing table with the new paths. This helps to make the sender nodes use the most updated valid paths and decreases the chances of using stale paths. The receiver node sends the RRREQ packet when predicting there is a prob- lem in previous paths and there is a need to update the sender. This is because the receiver node did not receive any data during the waiting time. The sender node in some cases did not receive the error packet, especially if the intermediate nodes cannot send the error packets dur- ing high traffic load or high mobility. This situation makes the sender node keep sending data packets through the invalid path. In that case, when the receiver node finds that no data packet has been received, it should update the sender node with a currently available path.
The second case is more involved. Reference  proposes a local routing algorithm for this case. The authors assume that the power needed for transmission and reception is a linear function of d α where d is distance between the two neighboring nodes and α is a parameter that depends on the physical environment. The authors make use of the GPS position information to transmit packets with the minimum required transmit energy. The key requirement of this technique is that the relative positions of nodes are known to all nodes in the MANET. However, this information may not be readily available. In addition, the GPS-based routing algorithm has two drawbacks. One is that GPS cannot provide nodes useful information about the physical environment (blockages, bit error rates, etc.) and the second is that the power dissipation overhead of the GPS device is an additional power draw on the battery source of the mobile node.
Mobilead-hocnetworks (MANETs) consist of a set of devices with wireless facility (nodes) that are connected together through wireless links. This type of network is suitable in applications with limited resources and time. Examples of applications in MANETs are include military, rescue and emergency, conferences and meetings. MANET is easy to deploy in fast and simple ways as it requires only two or more mobile nodes . In addition to MANET, there are different types of adhocnetworks, which are wireless sensor network (WSN) [2, 3], vehicular networks (VANET) , and underwater wireless networks . With these networks and with the absence of a base station, each node acts as a router that manages the network. It learns about the network and communicates with other nodes by responding with different data/control packets. As nodes have limited resources (i.e. limited battery life, memory, bandwidth), the communication life between them is limited and depends on the network environment (for example: static, dynamic, dense, congested, etc.).
Abstract : In MANET, meta-heuristic algorithm is the major role for selecting optimal route path and security. During optimal routing process the OLSR protocol is modified by using the Fruit Fly Optimization. The FFO algorithm is utilized to locate the ideal and best way to route. After choosing the optimal path Diffie-Hellman(DH) cryptography is used for secure data transmission in MobileAdhocNetworks. We have proposed an enhanced DH Cryptographic algorithm based on Particle Swarm Optimization (PSO) Technique for improving the performance of encryption and decryption process and we have shown that Qos of proposed work is better than existing works.
mobile node maintain routing table which contain list of all available destinations. These tables are updated by transmitting routing information periodically throughout the network. The advantage of maintaining routing table is that if routes are available in table then nodes can communicate with each other without any delay. If route is not available in the table for particular destination then packet should wait in a queue until node receives routing information related to its destination. When routing information is transmitted among nodes, large number of control signals is generated in the network. In highly dynamic environment, significantly large amount of resources are required to keeping the routing information up-to- date and. Widely known proactive routing protocols are Destination Sequence Distance Vector (DSDV), Optimized Link State Routing (OLSR), Wireless Routing Protocol (WRP).
shouts randomly the Host Controller Interface (HCI) which provides the convenient HCI_Inquiry or HCI_Write_Scan_Enables, that cause devices to enter to INQUIRY or INQUIRY SCAN, once the devices discover neighboring devices that are within range, a master-slave relationship is formed, then wait for the BASEBAND to accomplish communication among the nodes and then notify the BTAlgo according to befit matter (INQ_FINISH and PAGE_SCAN_FINISH). Then letting us know whet- her establish a connection with a distant device and decide to exchange data, or enter round procedures. Round pro- cedures happen periodically, which find the links, and determine which ones have failed and which ones are alive.
In recent studies, the objective is on the discovery of multipath and Quality of Service of the on-demand routing protocol. Ant colony-based multi-path QoS-aware routing (AMQR)  integrates link and disjoint multipath route and swarm intelligence to choose multiple paths for providing QOS . The on-demand multicast routing protocol (ODMRP) is a protocol based on mesh for mobileadhocnetworks. Due to its mesh based features, ODMRP has the capability to exploit redundant route also when the shortest route becomes invalid. Hence is the robustness of ODMRP to the mobility of host and failure of connectivity. Besides, the protocol overhead is reduced because the multicast route and maintenance of membership are completely on-demand. There are two phases, a request phase and a reply phase in ODMRP, just as in the other on-demand routing protocols. When a packet is sent for the first time to a multicast group, a JOIN REQUEST message is broadcasted to the total network by the sender. When a non-duplicate JOIN REQUEST message is received by a node, it saves the relevant upstream node ID in a backward learning technique, and then received JOIN REQUEST is rebroadcasted. When the non-duplicate JOIN REQUEST message is received by a multicast member, it verifies and updates its member table. Periodic rebroadcasting of a corresponding JOIN TABLE message is made by the receiver to its neighbor, if a valid entry is in
Routing in Bluetooth adhocnetworks also known as scatternets uses several techniques: cross-layer optimizations align the Bluetooth data link layer and network layer, hoping to incur little control overhead during communication . Liu et. al  implemented scatternet formation apart from routing to discover and form multihop routes using the master-slave restrictions imposed by the Bluetooth protocol. The scatternet formation technique is on-demand, only forming routes when needed. This way, the scatternet formation mechanism consumes less battery energy. Huang et. al  adapted AODV for Bluetooth using cross-layer optimization which assigns a load metric to the link between connected Bluetooth devices. Periodic HELLO packets are sent between the data link and network layers to assess link status.
These features help a lot in adhocmobilenetworks. Adhoc wireless networks consist of wireless nodes that can communicate with each other in the absence of a fixed infrastructure. Adhocnetworks, defined in a manner in which the network nodes are organized to provide pathways for data to be routed from the user to and from the desired destination. When cooperative communication emerged in adhoc network wireless nodes cooperate with each other in their transmissions to form a longer transmission link. This technique has attracted much attention as an effective technique to combat multi-path fading, enhance receiver reliability and achieve better energy efficiency of wireless communication systems in adhoc network .
836 In 2012, Chhagan Lal ,V.Laxmi, M.S.Gaur “A Node- Disjoint Multipath Routing method based on AODV protocol for MANETs” Frequent link failures square measure caused in mobilead-hocnetworks as a result of node’s quality and use of unreliable wireless channels for information transmission. As a result of this, multipath routing protocols become a very important analysis issue. During this paper, we have a tendency to propose and implement a node-disjoint multipath routingtechnique supported AODV protocol. The most goal of the planned technique is to see all on the market node-disjoint routes from supply to destination with minimum routing management overhead. With the planned approach, as shortly because the ﬁrst route for destination is set, the supply starts information transmission. All the opposite backup routes, if on the market, square measure determined at the same time with the information transmission through the ﬁrst route. This minimizes the initial delay caused as a result of information transmission is started as shortly as ﬁrst route is discovered.
end-to-end delay will be certainly noticed because the sudden loss of route when losing the current path to the destination . To deal with this issue, these problems have to be considered when designing a routing protocol. Routing protocols have to keep the overhead as low as possible, and find paths with less congestion. In addition, the protocols must be adaptive to frequent topology changes. In addition, the nodes have limited resources effect on the network performance especially the memory. For instance, when number of nodes increases, the traffic load becomes more in the middle of the topology and as a result the network becomes congested. Routing protocols needed to have an efficient mechanism to keep the source aware about new available paths.
Congestion occurs in mobileadhocnetworks (MANETs) with limited resources. In such networks, packet transmissions suffer from interference and fading, due to the shared wireless channel and dynamic topology. Transmission errors burden the network load. Recently, there has been increasing demand for support of multimedia communications in MANETs. The large amount of real-time traffic tends to be in bursts, is bandwidth intensive and liable to congestion. Congestion leads to packet losses and bandwidth degradation, and wastes time and energy on congestion recovery. A congestion-aware routing protocol can preempt congestion through bypassing the affected links. Wireless standards, such as IEEE 802.11a/b, support adap- tive transmission in MANETs to accommodate time-varying channels. However, in  the authors point out that, when operating under heavy traffic conditions (every node always has packets to transmit), IEEE 802.11 DCF provides long term per packet fairness in single-hop networks, which incurs a network performance anomaly: in a one-hop network, the active low data-rate nodes decrease the throughput of high data-rate nodes. One of the solutions to these decrease in throughput in multi-rate networks is to use multiple channels. Another solution, which is feasible in multi-hop networks, is to employ a routing protocol, which gives priority to higher data- rate links to build a route, to reduce the use of low data-rate nodes. Because low data-rate nodes have a lower probability of being used, the overall network throughput is improved.
The important characteristics of adhoc wireless net- works  are: dynamic topologies, low bandwidth, lim- ited battery power, decentralized control, weak physical protection, etc. Dynamic Topologies: The nodes in adhoc wireless networks are free to move independently in any direction. The network topology changes randomly at unpredictable times and primarily consists of bidirec- tional links. Low Bandwidth: These networks have lower capacity and shorter transmission range than fixed infra- structure networks. The throughput of wireless commu- nication is lesser than wired communication because of the effect of the multiple access, fading, noise, and inter- ference conditions. Limited Battery Power: The nodes or hosts operate on small batteries and other exhaustible means of energy. So, energy conservation is the most im- portant design optimization criteria. Decentralized Con- trol: Due to unreliable links, the working of adhoc wire- less network depends upon cooperation of participating nodes. Thus, implementation of any protocol that in- volves a centralized authority or administrator becomes difficult. Weak Physical Protection: Nodes in adhoc wire- less networks are usually compact, soft, and hand-held in nature. Today, portable devices like mobile phones or personal digital assistants (PDAs) are getting smaller and smaller. They could get damaged or lost or stolen easily and misused by an adversary.
In this paper, a novel hybrid protocol is proposed to recover the link failures by reconfiguring virtual backbone in MANETs. We describe the construction of reconfigurable virtual backbone and finding an on-demand route in case of link failures. The main objective of the proposed protocol is to minimize the routing overhead and maintenance cost. Based on the simulation results, we can conclude that the proposed RMR protocol yields better results in terms of packet delivery ratio, throughput, normalized overheads, delay, dropping ratio and overall residual energy by varying size of the network and traffic in comparison with existing protocols. In the future, we would like to enhance the proposed protocol by incorporating the security concepts to increase the reliability and confidentiality of the network. REFERENCES
There are many benefits of multicasting using with network. The communication cost reduced by multicasting for applications that sends the same data to many recipients instead of sending via multiple unicast. This paper gives a general survey of multicast routing protocols in Mobilead- hocNetworks (MANETs). The multicast routing protocols are divided into two categories- multicast routing based on application independence and multicast routing based on application dependence. Multicast routing protocols plays an important role in MANETs to provide group communication. Multicasting is one of the major communication technologies primarily designed for bandwidth conservation and an efficient way of transferring data to a group of receivers in wireless mesh networks.