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Delay tolerant network solves technical challenges in the heterogeneous network that may lack end-to-end connectivity. However, due to the disconnected paths, message delivery is much dependent on the cooperation of intermediate nodes, but malicious nodes may inject other nodes with either bogus messages or copies of good messages. This causes relaying of unwanted packets, which in turn leads to draining the energy of the intermediate nodes. This scenario may be termed as flooding attack. The paper discusses three types of flooding attacks, namely breadth attack (type 1), breadth attack (type 2), and depth attack. Breadth attack (type 1) refers to attack by those malicious nodes that relay only bogus messages, breadth attack (type 2) refers to the attack by those malicious nodes that relay both bogus and good messages, and depth attack refers to the attack by those malicious nodes that create copies of its own good messages and floods in the network. In this paper, we present a novel reputation based schemas that detect the flooding type of malicious nodes in DTNs. We propose three algorithms where first algorithm Reputation Algorithm handles a breadth attack (type 1), second algorithm Reputation with Good Messages over Total Messages Algorithm handles both breadth attacks (type 1 and type 2), and third algorithm, Reputation using Good Messages over Total Messages with Check message Generation Rate (RepGMTMwithCGR) is robust for (depth attack + breadth attack) flooding attack. The simulation study shows RepGMTMwithCGR defends all categories of flooding attack considered in this paper and there is the improvement of 20% in message delivery, 61% decrease in relaying, 49% decrease in message dropping and 63% decrease in energy consumption in the presence of 30% malicious nodes in the network. The algorithm shows increase in message latency by 2% but decreases message latency by 25% when compared to existing work. The protocols can be employed in monitoring systems using base stations in open environments. [ABSTRACT FROM AUTHOR]

The vehicular delay-tolerant network is the real-life application based area of Delay tolerant network where communication takes place using vehicular nodes and roadside units. The topology used in vehicular networks is highly dynamic by architecture due to the use of moving vehicular nodes. It operates in such a scenario where a direct path between source and destination remains absent on the most piece of the time. In case of non-existence of connected path vehicular delay-tolerant network works opportunistically and uses the same store, carry, and forward paradigm as Delay Tolerant Network. However, the routing protocols designed for vehicular delay-tolerant network faces crucial challenges like inadequate relay node, incomplete data transfer, a large number of packet drop, and uncertain delivery time. In this research paper, we propose a novel routing strategy for the vehicular delay-tolerant network. The proposed routing strategy selects efficient vehicular relay node for complete packet transfer and intelligently reduces the packet drop for timely packet delivery. We implement the proposed routing strategy in the ONE simulator; the ONE simulator provides an opportunistic environment for nodes. We analyze the performance of the proposed strategy under various simulations results using different parameters. The results show that the proposed strategy outperforms standard routing protocols in terms of considered parameters and provide an efficient solution for the problem of disconnection. [ABSTRACT FROM AUTHOR]

In traditional Mobile Adhoc Networks routing algorithms, the existence of a sustainable path between the source and destination is a crucial issue. These algorithms are shown to be unsuccessful in Delay Tolerant Networks (DTNs) since the network is almost disrupted, and then such a path is not guaranteed. Although Store-and-Forward routing approach has provided an adequate solution for these networks, it suffers from the large end-to-end delay and the additional traffic and communication costs incurring the network. This study presents an efficient single-copy home-based routing scheme for DTNs. Two different scenarios, referred as blind and semi-blind, are considered based on the amount of available knowledge about the destination. Simulation results presented in this paper demonstrate that the performance of the proposed scheme is closely approaching the unrestricted flooding algorithm, the Epidemic. Moreover, the proposed scheme provides a low communication cost, an outstanding end-to-end delay and a high successful delivery ratio as compared to state-of-art algorithms. [ABSTRACT FROM AUTHOR]

Mobile social networks are a type of delay tolerant network consists of a large number of mobile nodes with social characteristics. The pattern of data transmission and delivery across these networks is due to intermittent, storage, transport and forward connections. Therefore, relay nodes play an important role in these networks. One of the problems with these networks is that there is selfishness in relay nodes. Many algorithms have been proposed to detect and counteract these selfish nodes, but these methods have low detection rates. This paper presents an algorithm for finding selfish nodes and how to persuade them to collaborate based on the game theory. The simulation results show that the proposed method improved the correct detection rate compared to the other methods. First, it applies the Nash equilibrium to identify the selfish nodes and then using the credentials in the relay phase, it forces the selfish nodes to cooperate. The parameters and how the nodes are applied will increase the learning power of the system. The governing rules are applied to the inference system after the learning process. According to the results obtained at the datacenter of the Tabriz University, the improvement has been dramatic, with more than 98% of packets being transferred to the destination in due time and less than 2% of the them has been deleted from the network or their time to live was over. We tried to use the closest nodes to the destination with highest remaining energy to send the data. [ABSTRACT FROM AUTHOR]

Nowadays, vehicles have been equipped with various kinds of sensors which produce so called big data constantly. Among them, multimedia contents form the major part of the total generated data. They are usually shared among vehicles in a region of interest with less concerns on delay criteria. Therefore, to reduce cost, these data will be delivered using a carry-and-forward method in a Vehicular Delay Tolerant Network. Since the volume of these data is not negligible, not only delivery utility but also memory space usage must be considered while designing forwarding strategy. ThrowBoxes have been utilized to increase encountering opportunities. In this paper, we develop an optimal data packet assignment algorithms to achieve global maximum delivery utilities among ThrowBoxes. We evaluate the proposed scheme with the real world data trace. The results show that our scheme achieves better performance in terms of delay, delivery ratio, cost and other metrics. [ABSTRACT FROM AUTHOR]

Opportunistic routing is a promising routing paradigm which increases the network throughput. It forces the sender's neighbors, who successfully overheard the transmitted packet, to participate in the packet forwarding process as intermediate forwarding nodes. As a seminal opportunistic routing protocol, MORE combines network coding idea with opportunistic routing to eliminate the need for strict coordination among active forwarding nodes. In this paper, we show that MORE performance does not scale well with the route length, especially when the route length goes beyond two hops. Also, we found that MORE fails to establish a working opportunistic route in sparse networks. Clearly, the network throughput is directly influenced by both the quantity and quality of forwarding nodes, and their cooperation order. In this paper, we propose a new forwarder selection mechanism which considers the route length, link qualities, the distance from the source, and nodes density. It eliminates the occasional route disconnectivity happening in MORE and improves the quality of the established opportunistic routes. The simulation result indicates that our proposal always outperforms MORE when dealing with long opportunistic routes. [ABSTRACT FROM AUTHOR]

Intermittently connected mobile networks (ICMNs) serve as an important network model for many critical applications. This paper focuses on a continuous ICMN model where the pair-wise contact process between network nodes follows a homogeneous and independent Poisson process. This ICMN model is known to serve as a good approximation to a class of important ICMNs with mobility models like random waypoint and random direction, so it is widely adopted in the performance study of ICMNs. This paper studies the throughput capacity and delay-throughput tradeoff in the considered ICMNs with Poisson contact process. For the concerned ICMN, we first derive an exact expression of its throughput capacity based on the pairwise contact rate therein and analyze the expected end-to-end packet delay under a routing algorithm that can achieve the throughput capacity. We then explore the inherent tradeoff between delay and throughput and establish a necessary condition for such tradeoff that holds under any routing algorithm in the ICMN. To illustrate the applicability of the theoretical results, case studies are further conducted for the random waypoint and random direction mobility models. Finally, simulation and numerical results are provided to verify our theoretical capacity/delay results and to illustrate our findings. [ABSTRACT FROM AUTHOR]

In recent years, more and more people begin to focus on data delivery through opportunistic contacts among mobile users. In most cases, the data that we expect to share with others are videos, such as popular music videos and funny films. Because the video delivery will consume numerous resources of devices, few people will provide such service for others without any benefit. Thus, this paper centers on the incentive mechanism design for video delivery in opportunistic networks. Although several incentive schemes for such kind of networks have been proposed, however, they all mainly focus on the encouragement of general data forwarding, and almost none of them aims to stimulate nodes to realize the performance objective of networks. In this paper, we propose Videocent, a novel quality-oriented incentive mechanism for video delivery, which takes the characteristics of video data into account and formulates the video delivery among nodes as a game. This mechanism could not only encourage nodes to participate in the video delivery but also stimulate them to follow the defined rules to optimize the video delivery quality of whole networks. Its performance is validated through extensive simulations. [ABSTRACT FROM AUTHOR]

Multicasting for delay-tolerant networks (DTNs) in sparse social network scenarios is a challenge due to the deficiency of end-to-end paths. In social network scenarios, the behaviors of their nodes are controlled by human beings, and node mobility is the same as that of humans. To design the multicasting algorithms for DTNs, therefore, it would be promising to capture the intrinsic characteristics of relationships among these nodes. In this paper, multicasting in DTNs is regarded as a message dissemination issue in social networks, and an egocentric network focused community aware multicast routing algorithm (ENCAR) is proposed. As distinct from some social-based routing algorithms which only focus on centrality analysis, ENCAR is an utility based and hierarchical routing algorithm, its utility function is constructed on the basis of centrality analysis and destination-oriented contact probability. We take notice of clustering phenomenon in social networks, and present the community aware forwarding schemes. In addition, to simulate the mobility of individuals in social networks, a novel community based random way point mobility model is also presented. In this paper, the performance of ENCAR is theoretically analyzed and further evaluated on simulator ONE. Simulation results show that ENCAR outperforms most of the existing multicast routing algorithms in routing overhead, on condition that delivery ratio is relatively high, with other significant parameters guaranteed to perform well. [ABSTRACT FROM AUTHOR]

Typically, delay tolerant network (DTN) suffers from frequent disruption, high latency, and lack of stable connections between nodes. As a special case of DTN, vehicular delay tolerant network (VDTN) has particular spatial-temporal characteristics. Different kinds of vehicles may have different movement ranges and movement patterns and the movements of vehicles exhibit significant dynamics from the temporal view. The movement patterns and dynamic characteristics of vehicles are difficult to be described accurately. To this end, a novel framework of VDTN routing algorithm based on trajectory clustering and dynamic Bayesian network (DBN) is proposed, which can capture the spatial-temporal characteristics and the movement patterns of vehicles in the real VDTN scenarios. Firstly, a K-means trajectory clustering (KTC) algorithm is adopted to cluster the trajectories of vehicles according to their spatial characteristics. Then, a KTC-based DBN structure learning algorithm is proposed to construct the prior network and transition network of DBN by an extended K2 + algorithm to capture the temporal characteristics of VDTN, and multiple DBN models are established for different trajectory clusters to further improve the prediction accuracy. Finally, a VDTN routing algorithm is presented to forward message by the inference of DBN models. Simulation results show that the proposed VDTN routing algorithm has a higher delivery ratio as well as a lower overhead compared with other related routing algorithms, and the effectiveness of the trajectory clustering method and DBN models are verified. [ABSTRACT FROM AUTHOR]

Profile-cast provides a novel data dissemination paradigm in mobile opportunistic networks, allowing messages to be disseminated to nodes based on their profiles rather than network identities. Profile-cast has attracted increasing attention, but most of existing algorithms cannot account for some scenarios where multiple attributes need to be considered simultaneously in a profile. We focus on the multi-attribute profile-cast (MapCast) paradigm, where the node's profile is represented by a multi-dimensional vector, which may contain multiple attributes of the node such as its behavior, interest, social information, etc. First, we consider a scenario with a fixed source node. We construct a message dissemination tree using the node encounter history. Then we propose a dissemination tree based MapCast algorithm, which adapts a heuristic search algorithm to select relay nodes so that the destination node can receive the message as soon as possible and the network has a low overhead. Second, we consider a more complex scenario with unfixed source nodes. In this scenario, the concept of group profile is defined, and a new high-efficient algorithm, group-profile based MapCast (G-MapCast), is proposed to limit the scope of message forwarding to the nodes whose profile or group profile satisfies certain delivery conditions. To further reduce the network overhead, we propose a network coding based MapCast algorithm on the basis of G-MapCast. Finally, we provide simulation results based on two real human contact datasets and verify the effectiveness and superiority of our algorithms. [ABSTRACT FROM AUTHOR]

Neighbour discovery plays a crucial role for communication in sparsely dense mobile networks, especially in delay tolerant networks, where neighbour discovery latency is generally much higher than the node contact duration. Hence, energy efficient neighbour discovery is an essential aspect of this type of network. Synchronous wake-up scheduling of the nodes can be used to decrease the neighbour discovery latency, but such scheduling cannot be applied to delay tolerant networks where the essence of the communication lies in it's decentralization. Additionally, the synchronous process needs a global clock for node synchronization. Using a global clock is an energy hungry process. Hence, to avoid this energy hungriness, over the years, many asynchronous protocols based on wake-up scheduling have been developed in order to timely wake-up the nodes to ease the neighbour discovery process in an energy efficient manner. However, asynchronous protocols have reduced message delivery and are not fine-grained enough to support high delivery ratio. In this paper, we have used a binary Galois field based technique for designing asynchronous wake-up scheduling. A thorough analysis has been performed to demonstrate the performance of this asynchronous protocol when compared to the current state of the art in the adaptive and the non-adaptive mode. Results show that the proposed protocol in non-adaptive mode increases message delivery probability by 10% and reduces message delivery latency approximately by 7% while keeping the energy consumption constant when compared to the other existing asynchronous protocols. [ABSTRACT FROM AUTHOR]

The proliferation of wireless mobile devices encourages research into their employment to form delay tolerant networks (DTN) for such applications as disaster response, military communications, and crowdsourcing. Within a DTN, messages are exchanged between nodes following a store-carry-forward paradigm, which is notably susceptible to congestion and can lead to a crippling in network performance. A DTN's time-dynamic topology departs from traditional network definitions in its unpredictable and volatile nature, thus prohibiting the effective adoption of traditional network solutions to this problem. In this paper, the Catora system is proposed as a multi-copy message exchange and buffer management system designed to both aid in the delivery of prioritized messages and mitigate congestion and its degradation. Operating around the distinct ordering of messages for transfer, delivery, and deletion, Catora propagates messages so as to balance their dissemination, hasten the delivery of high priority messages, and avoid congestion through strategic buffer management. Simulations using two real-world datasets demonstrate Catora's capability to quickly deliver more messages at reduced overhead costs when compared to benchmarks and the state-of-the-art, even when the network suffers from congestion. [ABSTRACT FROM AUTHOR]

In the internet of things (IoT) based wireless sensor network (WSN), the nodes are scattered to segregate the rapt data in the relevant field of application. In general, sensor nodes of IoT possess heterogeneous property and display cluster-based routing to transmit the data as it is considered as an efficient routing method. When one or more cluster heads (CHs) fail, the sensed data of sensor nodes that are currently serving cannot be forwarded by the faulty CHs. Consequently, data of the IoT application will not be sufficiently sensed by the sink node (gateway). As a result, information processing of this field will be affected profusely. This paper focuses on the development of a paired cluster fault-tolerant disjoint path routing in a path graph and a novel approach to solve this dilemma in polynomial time of the degree of the graph. The objective of this proposed IoT–WSN architecture is to diminish the latency, end-to-end delay as well as energy consumption and thereby improving the performance in terms of throughput and packet delivery ratio. The performance of this proposed method in IoT–WSN network is measured and affirmed using benchmark network simulator. [ABSTRACT FROM AUTHOR]

Routing in Opportunistic Internet of Things networks (OppIoTs) is a challenging task because of intermittent connectivity between devices and the lack of a fixed path between the source and destination of messages. Recently, machine learning (ML) and reinforcement learning (RL) have been used with great success to automate processes in a number of different problem domains. In this paper, we seek to fully automate the OppIoT routing process by using the Policy Iteration algorithm to maximize the possibility of message delivery. Moreover, we model the OppIoT environment as a Markov decision process (MDP) replete with states, actions, rewards, and transition probabilities. The proposed routing protocol, RLProph, is able to optimize the routing process via the optimal policy obtained by solving the MDP using Policy Iteration. Through extensive simulations, we show that RLProph outperforms a number of ML-based and context-aware routing protocols on a multitude of performance criteria. [ABSTRACT FROM AUTHOR]

Location information of a sensor node is the primary concern to process the sensed data in Wireless Sensor Networks (WSNs). The location of the sensor node is used in other domains of sensor network like message routing, node tracking, load balancing. For statically deployed sensor nodes, mobile anchor based localization is an efficient solution. The main challenge in mobile anchor based localization is designing an optimum path for the mobile anchor node considering the coverage, path length and localizability of sensor nodes as the key features. In this paper, we propose a novel path planning approach for mobile anchor based localization called "M-Curves". Our proposed model promises that all the nodes in the network will receive at least three non-collinear beacon messages for localization. Our proposed trajectory assures full coverage, high localization accuracy as compared to other static models. Also, we optimize the localization process by using Dolphin Swarm Algorithm(DSA). The fitness function used for optimization in DSA, minimizes the localization error of the node in the network. [ABSTRACT FROM AUTHOR]

Geographic routing in wireless sensor networks brings numerous inherent advantages, albeit its performance relying heavily on accurate node locations. In mobile networks, localization of the continuously moving nodes is a challenging task and location errors are inevitable and affect considerably routing decisions. Our proposal is in response to the unrealistic assumption widely made by previous geographic routing protocols that the accurate location of mobile nodes can be obtained at any time. Such idealized assumption results in under-performing or infeasible routing protocols for the real world applications. In this paper, we propose INTEGER, a localization method intertwined with a new location-error-resilient geographic routing specifically designed for mobile sensor networks even when these networks are intermittently connected. By combining the localization phase with the geographic routing process, INTEGER can select a relay node based on nodes' mobility predictions from the localization phase. Results show that INTEGER improves the efficiency of the routing by increasing the packet delivery ratio and by reducing the energy consumption while minimizing the number of relay nodes compared to six prevalent protocols from the literature. [ABSTRACT FROM AUTHOR]

Vehicular ad hoc networks have been used for improving driving experiences by providing safety, efficiency and infotainment applications. Due to high mobility of vehicles, network topology changes frequently, and highly dynamic topology results in lost connection. The geographic routing protocol is used since it does not rely on the establishment of topology. With the popularity of heterogeneous wireless network links, heterogeneous communication range should be taken into consideration when selecting relay from candidate set. The greedy geographic routing protocol with the principle of selecting nearest node to destination may not ensure high packet delivery ratio and low end-to-end delay in this situation. This paper proposes a GPSR-based routing protocol called ETD-GPSR which incorporates the metric expected transmission delay (ETD) for data dissemination with heterogeneous communication range in VANETs. The neighbor table with asymmetric wireless links is established with the help of acknowledgement lists and intermediate nodes. Thus, potential good forward links overshadowed by poor reverse links can be found during the periodic beacon message exchange. Attaching each link with expected transmission delay which takes link quality, link delay and communication range into consideration, the vehicle with the minimum ETD is selected as next hop. Simulation results show that in urban environment with heterogeneous communication range, using the metric ETD has increased the packet delivery ratio and decreased the end-to-end delay. [ABSTRACT FROM AUTHOR]

Mobile social networks are among subsets of delay tolerant networks. The nodes of these networks are mobile and the communication between them is done wireless and all nodes have social characteristics. The connection between these nodes is temporary and there is not end to end route between the source and the destination. Therefore, it is difficult to deliver the packets to the destination. One of the best routing methods in such networks is to use the information about the network context. These methods require the process of information collection and replicate the packets based on the context to increase the delivery ratio and enforce great overhead onto the network. Since the nodes have social characteristics and these features exist within the network, it seems that using them within the routing can be useful. In this paper a community based method of delivering is proposed that uses social characteristics of the individual members for routing the packets. Using the predetermined roles for the members that do not need data collection level can improve routing in these networks. In this method a tree is formed and each group of the members is entitled in one branch of it. The transmission of the packets from the source to the destination is done based on the differences between their characteristics and through the route which has the highest number of the nodes. The simulation results show that the delivery ratio of this method has increased regarding the related works and the overhead ratio has decreased. [ABSTRACT FROM AUTHOR]

Flooding is one of the most important operations in mobile ad hoc networks. There are two strategies for existing flooding algorithms to make the forwarding decision. The first strategy is sender-based, where a forwarding node is in charge of determining its next-hop forwarding nodes. Existing sender-based algorithms can achieve linear computation overhead for each node, but this is at the expense of the transmission redundancy. The second strategy is receiver-based, where a node makes the forwarding decision of itself when it receives the flooding message. Receiver-based flooding algorithms perform well on reducing redundancy of transmissions, but each node requires at least O (n 2) computations, where n is its number of neighbors. In this paper, we show that a receiver-based algorithm can achieve both good performance and low computation overhead at the same time. We first introduce an efficient O(nlogn) algorithm, RBF. Second, two extensions of RBF, RBF-E1 and RBF-E2, were proposed. RBF-E1 has outstanding performance (1) in 3D wireless networks, and (2) when the defer time is short. RBF-E2 further reduces the computation overhead for each node to O(n). The proposed algorithms require only one-hop neighbor location information to make the forwarding decision. Extensive simulations are carried out to evaluate the performance of our algorithms. [ABSTRACT FROM AUTHOR]

Enhancing the quality of service is the crucial issue of future wireless networks. In this paper, we propose a new multihop wireless routing protocol inspired by opportunistic resource allocation strategies that take into account the variability of the radio conditions due to path loss, shadowing and multipath fading. Thanks to this knowledge, our proposition dynamically adapts the selected path accross time. The adaptation is function of each link state and the amount of channel information available. This allows to improve system performance in terms of delay and throughput. This solution can be used in all multihop wireless contexts but can have a special interest in wireless coverage zone extension context. Simulation results will show that the proposed routing protocol greatly outperforms the other existing protocols such as ad-hoc on-demand distance vector, optimized link state routing and extremely opportunistic routing protocols reducing mean packet delays by more than 50% in several scenarii. [ABSTRACT FROM AUTHOR]

On-demand routing protocols discover routes through network-wide searches. Route requests are broadcast to a large number of nodes, and route replies may contain long routes. In this paper, we address the route discovery problem and aim to reduce route discovery overhead. We propose using data packets to discover routes. A source sets a boolean variable in a data packet to be true when it has only one route to the destination. This variable is a new form of a route request. The nodes forwarding the data packet send route replies containing cached routes. To prevent nodes from sending duplicate routes to the source, we define a forward list and a backward list in the data packet. The node sending a route reply records route diverging and converging information about the route in the route reply. Subsequent nodes use the information in the data packet to decide whether to send a route reply. Our algorithm reduces route discovery latency and discovers routes shorter than or having the same length as the active data path. Due to these shorter routes, it reduces the total size of route requests and route replies significantly. Routing overhead increases slowly as mobility or network load increases. Our algorithm is independent of node movement. It improves packet delivery ratio by 15% and reduces latency by 54% for the 100-node networks at node mean speed of 20 m/s. [ABSTRACT FROM AUTHOR]

Rare existence of the end-to-end path and intermittent connectivity among the nodes are the key characteristics of delay tolerant networks (DTNs). Such networks are potentially applicable in challenged environment like post-disaster situation, where traditional communication infrastructure is partially or fully absent. Significant research efforts are made to develop data forwarding schemes which are efficient in terms of delivery ratio in DTNs. However, fairness in message delivery is a less investigated topic in DTN routing. In most of the traditional data forwarding schemes, delivery of a message varies depending on its destination. Each destination in the network may not receive its intended messages with the same success rate. But in real-life applications, e.g. post-disaster environment, fair delivery of the messages to each destination is imperative for conducting relief operations properly. In this paper, we address the issue of fairness in message delivery in DTNs. In order to achieve fairness in message delivery, we analyze the influence of important parameters on successful message delivery. Based on this analysis, we design a metric for relay selection and subsequently propose a relay selection scheme for fair message delivery in DTNs. Performance of our proposed scheme is evaluated in ONE simulator considering realistic node-mobility map based on a recent post-disaster situation. Comparative results show that the proposed scheme achieves more impressive fairness in message delivery than the other competing schemes while achieving acceptable delivery ratio and low overhead ratio in the network. [ABSTRACT FROM AUTHOR]

Communication protocols generally rely on the existence of very long multihop paths to reach distant nodes. They disregard, however, how often such paths indeed occur, and how long they persist, especially in highly dynamic mobile networks. In this direction, this paper evaluates quantitatively the influence of node relative speed on path establishment and maintenance, using real and synthetic vehicular network traces. We propose a methodology for vehicular network analysis where both relative speeds and hop distances are used as parameters to characterize node vicinity. Results show that contact opportunities highly depend on the relative speed and the hop distance between nodes. In sparser scenarios, the number of contacts between nodes separated by more than 3 hops or even between neighbors with relative speed above 40 km/h is negligible. This confirms the intuition that contacts at lower relative speeds and at few hop distances happen more often. In addition, contacts last longer as the number of hops between nodes decreases. Nevertheless, we can still find multihop paths able to transmit messages at high relative speeds, even though less often. We also demonstrate that relative speeds reduce the number of useful contacts more severely when compared to the hop distance. For last, we show that it is possible to increase the number of successful packet transmissions by simply applying the outcomes of this work, without any sophisticated model, avoiding the waste of resources, such as energy and bandwidth. [ABSTRACT FROM AUTHOR]

In delay tolerant vehicular networks, gossip is an efficient forwarding scheme, which significantly reduces the message transmission overhead while maintaining a relatively high transmission rate in the high mobility vehicular environment. This mechanism requires vehicles as the network nodes to forward messages according to the system-defined gossip probability in a cooperative and selfless way among all the vehicles in the system. However, in the real word vehicular networks, most of the vehicular nodes exhibit selfish and non-collaboration behaviors to reduce the gossip probability in order to save their own energy and other limited resources in the vehicular nodes. In this paper, we study how node selfishness influences the performance of energy-constrained gossip forwarding based vehicular networks. We consider two typical forms of selfishness in the realistic vehicular networks: individual selfishness and social selfishness, and study the networking performance by focusing on the average message transmission delay and mean transmission cost. First, we model the message transmission process with selfish behaviors in the gossip forwarding based delay tolerant vehicular networks using a continuous time Markov chain. Based on this useful model, we derive closed-form formulae for average message transmission delay and mean transmission cost. Then, we give extensive numerical results to analyze the impact of selfishness on system performance of the vehicular networks. The results show that gossip forwarding in delay tolerant vehicular networks is robust to selfish behaviors since even when they increase the message transmission delay, there is a gain on the message transmission cost. [ABSTRACT FROM AUTHOR]

Traditional data broadcasting schemes in delay tolerant networks assume that mobile users can only retrieve one data item in each time slot. In this paper, we propose a novel data broadcasting framework in the delay tolerant networks that exploits the concept of network coding to mix the delivered data items according to the user's stored data items. Our approach enables a user to encode multiple data items dynamically in each time slot, and allows each user with a mobile device to retrieve a data item by using locally stored data items to decode the encoding data. Specifically, we design an algorithm called Preference-Aware Coding (PAC) to select the data items to be encoded in each time slot. The objective is to serve the maximal number of mobile users with the encoding data and minimize the access time required for data broadcasting in the delay tolerant networks. The algorithm avoids encoding unnecessary data in each time slot to reduce the access delay. We empirically implement the framework in the real delay tolerant networks, and simulation results show that the PAC algorithm can reduce the access time of the traditional scheme by 42 % on average. [ABSTRACT FROM AUTHOR]

Delay tolerant networks (DTNs) are characterized by delay and intermittent connectivity. Satisfactory network functioning in a DTN relies heavily on co-ordination among participating nodes. However, in practice, such co-ordination cannot be taken for granted due to possible misbehaviour by relay nodes. Routing in a DTN is, therefore, vulnerable to various attacks, which adversely affect network performance. Several strategies have been proposed in the literature to alleviate such vulnerabilities-they vary widely in terms of throughput, detection time, overhead etc. One key challenge is to arrive at a tradeoff between detection time and overhead. We observe that the existing table-based reactive strategies to combat Denial-of-service (DoS) attacks in DTN suffer from two major drawbacks: high overhead and slow detection. In this paper, we propose three secure, light-weight and time-efficient routing algorithms for detecting DoS attacks (Blackhole and Grey-hole attacks) in the Spray & Focus routing protocol. The proposed algorithms are based on use of a small fraction of privileged (trusted) nodes. The first strategy, called TN, outperforms the existing table-based strategy with 20-30 % lesser detection time, 20-25 % higher malicious node detection and negligible overhead. The other two strategies, CTN_MI and CTN_RF explore the novel idea that trusted nodes are able to utilize each others' information/experience using their long range connectivity as and when available. Simulations performed using an enhanced ONE simulator reveals that investing in enabling connectivity among trusted nodes (as in CTN_RF) can have significant performance benefits. [ABSTRACT FROM AUTHOR]

Being a member of the post quantum cryptography family, multivariate public key cryptographic (MPKC) system enjoys many useful properties such as fast implementation and moderate resources requirement, which is quite suitable for the wireless sensor network (WSN). However, MPKC system requires the usage of large public and private keys to ensure security which makes it inapplicable to wireless sensors with very limited system resources. In this paper, we propose an online/offline signature scheme based on a well known MPKC scheme: unbalanced oil and vinegar signature scheme for the wireless sensor network. Our scheme can reduce the cost of hardware running on signing process and the storage space of private key in the online signing phase. What is more, by combining a recent technique, the total storage requirement in a WSN node reduces by 85.8 % for the recommended parameters, which makes our new scheme feasible for the practical deployment on the WSN platforms. [ABSTRACT FROM AUTHOR]

In today's world, when every mobile device corresponds with human behavioral patterns. People often come across with various communities having patterns such as mobility, communication and groups. Trust is an intrinsic factor, which plays important role in formation of such communities. It is important to see the inherent risk involved in such socially active communities. Such factors motivate the use of trust as a routing factor in Delay Tolerant Networks (DTNs). This paper proposes a Trust based Intelligent Routing Algorithm, which exploits the Call Data Record from Call Detail Record. The function of Artificial Neural Network is to calculate and learn, trust value that can be shared among network devices. Our algorithm lowers the need of nodes resources like energy consumption, computation time and space overheads. The proposed algorithm enhances the routing performance in DTN. The earlier work claiming better efficiency generally ends up consuming network's resources. On the contrary our proposed algorithm provides in-built security, without any additional overhead. To the best of our knowledge the proposed work is the first of its kind, providing ingrained security feature to the DTN. This work gives vantage point to the researchers in the field over other schemes proposed in the past. [ABSTRACT FROM AUTHOR]

Provisioning buffer management mechanism is especially crucial in resource-constrained delay tolerant networks (DTNs) as maximum data delivery ratio with minimum overhead is expected in highly congested environments. However, most DTN protocols do not consider resource limitations (e.g., buffer, bandwidth) and hence, results in performance degradation. To strangle and mitigate the impact of frequent buffer overflows, this paper presents an adaptive and efficient buffer management scheme called size-aware drop (SAD) that strives to improve buffer utilization and avoid unnecessary message drops. To improve data delivery ratio, SAD exactly determines the requirement based on differential of newly arrived message(s) and available space. To vacate inevitable space from a congested buffer, SAD strives to avoid redundant message drops and deliberate to pick and discard most appropriate message(s) to minimize overhead. The performance of SAD is validated through extensive simulations in realistic environments (i.e., resource-constrained and congested) with different mobility models (i.e., Random Waypoint and disaster). Simulation results demonstrate the performance supremacy of SAD in terms of delivery probability and overhead ratio besides other metrics when compared to contemporary schemes based on Epidemic (DOA and DLA) and PRoPHET (SHLI and MOFO). [ABSTRACT FROM AUTHOR]

Mobile sensing emerges as an important application for mobile networks. Smartphones equipped with sensors are used to monitor a diverse range of human activities. One key and challenging procedure of the mobile sensing applications is data gathering, where the sensed data from distributed mobile nodes are captured and uploaded to the cloud or base station for further processing. Yet the mobile sensing application, which usually periodically generates some sensed data, would definitely deteriorate the 3G quality because the network cannot cope with the high demand; and users would be charged at high prices by using the 3G channel, which makes the mobile sensing application infeasible. In this paper, we proposed a hybrid data gathering and offloading algorithm DGO for the mobile sensing applications. Besides the direct uploading through 3G or Wifi offloading, the sensed data could also be forwarded to other peer nodes through short range communications. Nodes collect meta-data such as remaining energy, contact regularity, and expected contact duration to calculate the upload/offload utility and upload priority for data segments. Based on these utility factors, each data segment could decide its own approach at a specific time for uploading. Experimental studies show that DGO is efficient in data gathering and data offloading in mobile sensing applications. Given the low accessibility of Wifi APs, DGO still gains about more than 30 % of data offloading compared with existing algorithms without much extra transmission overhead or delay. [ABSTRACT FROM AUTHOR]

The storage resources and communication opportunities in space delay/disruption tolerant networks (DTN) are usually very limited. Moreover, as the links in space DTN are often subject to long delay, intermittent connectivity and asymmetric bandwidth, end-to-end continuous path may not be guaranteed and messages may stay at intermediate nodes for a long time. Thus, congestion in space DTN, which takes the form of persistent storage exhaustion, is inevitable. Due to the intrinsic features of space DTN, congestion control should be performed with local information before congestion occurs and limited storage and communication resources should be allocated to messages that have the highest probability to be delivered to destination. Based on these principles, a local information-based congestion control (LCC) scheme for space DTN is proposed in this paper. Firstly, LCC attempts to relieve the storage pressure by using alternative paths i.e. non-best paths when the network is about to congest. Secondly, LCC adopts a utility function based on the reciprocal of hop counts to destination to assist forwarding decision and queue management. Simulation results show that with the combination of LCC typical space DTN routing algorithm can achieve higher message delivery ratio and more uniform traffic distribution. [ABSTRACT FROM AUTHOR]

Mobile ad hoc networks are a subset of delay tolerant networks (DTNs) composed of several mobile devices. These dynamic environments make conventional security algorithms unreliable; nodes located far apart from each other may not have access (available) to each other's public keys or have doubt on the validity of public-keys, making secure message exchange difficult. Furthermore, ad hoc networks are likely to be highly compromised and therefore may be untrusted. Other security methods, such as identity-based encryption and Kerberos, rely on requesting key data from a trusted third party, which can be unavailable or compromised in a DTN like environment. The purpose of this paper is to introduce two security overlay networks capable of delivering messages securely, preventing both eavesdropping and alteration of messages. The first algorithm, Chaining, uses multiple midpoints to re-encrypt the message for the destination node. The second, Fragmenting, separates the message key into pieces that are routed and secured independently from each other. Both techniques improve security in hostile environments; under test conditions, Chaining reduces the number of messages intercepted by 90 %, and Fragmenting by 83 %. This improvement has a performance trade-off, however, reducing the delivery ratio by 63 % in both algorithms. [ABSTRACT FROM AUTHOR]

In recent years, several investigations have been made on ' challenged network' [also known as, delay tolerant network (DTN)] architectures highlighting their advantages and disadvantages. In spite of its inherent shortcomings of unreliability and delay, smart-phone based opportunistic network is gaining immense popularity in the research community due to its applicability in different adverse and extreme communication scenarios where traditional communication infrastructure is either unavailable or incapacitated for a long time. Considerable research has been conducted till date to design efficient network architecture for emergency data dissemination in intermittently connected/challenged networks. Different architectures (ranging from flat to multi-tier) are proposed for implementing opportunistic DTN keeping in view of specific application requirements. However, very few of these proposed architectures have been examined from the perspective of a post disaster communication. Moreover, most DTN architectures are designed by aiming towards increasing delivery probability and reducing latency and as a whole, maximizing network throughput; with very little emphasis on its energy efficiency. The impact of different mobility patterns on existing DTN routing algorithms with respect to data dissemination and energy consumption has also not been studied so far. Our objective, in this paper, is to investigate the impact of different mobility patterns on existing DTN routing protocols and existing DTN architectures and subsequently, come up with a suitable energy efficient DTN framework combining suitable architecture and routing protocol that may be used to offer different disaster management services during post-disaster relief operation. We have done an extensive simulation on ONE simulator with different categories of well-known existing DTN architectures, mobility models, DTN routing protocols to study the network performance in terms of delivery probability, energy efficiency and overhead ratio. Based on the simulation results, we have tried to figure out a suitable combination of energy efficient architecture, mobility model and routing protocol that fits well in the post disaster communication scenario. [ABSTRACT FROM AUTHOR]

Recent advances in mobile communication shows proliferation in networks formed by human carried devices known as the pocket switched network (PSN). Human beings are social animals. They tend to form groups and communities, and have repetitive mobility pattern which can be used to disseminate information in PSNs. In this paper, we give a deeper insight to the nature of community formation and how such information can be used to help opportunistic forwarding in mobile opportunistic networks. Using real world mobility traces, we first derive the adjacency list for each node and form the contact graph. Using tools from social network analysis we then determine various node properties like centrality and clustering coefficient and graph properties like average path length and modularity. Based on the derived graph properties, node encounter process and nature of message dissemination in PSNs, we propose two social based routing, known as the contact based routing and community aware two-hop routing. We compare the proposed routing techniques with generic epidemic and prophet routing and Bubble-Rap, a social based routing. Results show that the proposed algorithms is able to achieve better delivery ratio and lower delay than Bubble Rap, while reducing the high overhead ratio of epidemic and prophet routing. [ABSTRACT FROM AUTHOR]

In order to understand the message dissemination performance in delay-tolerant networks, much analysis work has been proposed in literature. However, existing work shares a common simplification that the pairwise inter-meeting time between any two mobile nodes is exponentially distributed. Not mention the fact that such assumption is only an approximation, it cannot be applied by network planners to directly control the mobile nodes for any network optimization, e.g., energy efficiency. It is quite significant to study the relationship between the network performance with the parameters that can be adjusted directly to tackle the limitations of current exponential distribution assumption based analysis. Therefore, in this paper, we are motivated to jointly consider the transmission range and messages residence time to stochastically analyze deadline-constrained message delivery ratio utilizing a controlled epidemic routing. The message propagation is considered as an age-structure process and described by a susceptible-infectious-recovered model, which is then analyzed using delay differential equations. Since both the transmission range and the message residence time are related to the mobile nodes' energy consumption, we further apply our analysis framework to investigate the tradeoff between the energy consumption and the achievable message delivery ratio. The correctness and accuracy of our analysis are validated by extensive simulations. [ABSTRACT FROM AUTHOR]

The performance modeling study of Delay-Tolerant Network routing, in general, assumes the nodes to be homogeneous (in terms of features such as the coverage range) and uncompromised (in terms of forwarding messages). However, in realistic settings this may not be the case. The routing performance modeling of such realistic scenarios that involve multifariously-featured and egotistic nodes would be interesting and insightful. To this end, in this paper, we analytically model the routing behavior of such nodes using Ordinary Differential Equations for two different routing protocols namely, Epidemic Routing and Two-Hop Routing. Furthermore, we also study the degradation in the routing performance caused by an increase in the fraction of selfish nodes present in the heterogeneous node population. The proposed analytical model is validated via extensive simulations. [ABSTRACT FROM AUTHOR]

Delay/disruption tolerant networking (DTN) was developed to enable automated network communications despite the long link delay and frequent link disruptions that generally characterize space communications. The performance of DTN convergence layer adapter (CLA) protocols over asymmetric space communication channels has not yet been comprehensively characterized. In this paper, we present an experimental performance evaluation of DTN CLA protocols for reliable data transport over a space communication infrastructure involving asymmetric channel rates, with particular attention to the recently developed Licklider transmission protocol (LTP) CLA (i.e., LTPCL). The performance of LTPCL is evaluated in comparison with other two reliable CLAs, TCP CLA and a hybrid of TCP CLA and LTPCL, for long-delay cislunar communications in the presence of highly asymmetric channel rates. LTPCL is also evaluated and analyzed in a deep-space communication scenario characterized by a very long link delay and lengthy link disruptions. [ABSTRACT FROM AUTHOR]

This paper introduces a novel multi-copy routing protocol, called predict and forward (PF), for delay tolerant networks, which aims to explore the possibility of using mobile nodes as message carriers for end-to-end delivery of the messages. With PF, the message forwarding decision is made by manipulating the probability distribution of future inter-contact and contact durations based on the network status, including wireless link condition and nodal buffer availability. In particular, PF is based on the observations that the node mobility behavior is semi-deterministic and could be predicted once there is sufficient mobility history information. We implemented the proposed protocol and compared it with a number of existing encounter-based routing approaches in terms of delivery delay, delivery ratio, and the number of transmissions required for message delivery. The simulation results show that PF outperforms all the counterpart multi-copy encounter-based routing protocols considered in the study. [ABSTRACT FROM AUTHOR]

Delay tolerance network probabilistic routing protocols forward message to a node by observing its predictability value to meet the message destination. However, it is vital to predict the ability of node to carry the transmitted message. For instance, the traffic confluence on the high probable nodes can produce congestion that results in the drop of previously stored messages. These drops diminish the delivery ratio because the dropped message lost its opportunity to be delivered. Since, there exist multiple copies of each message; therefore, the same node invariably receives the dropped messages from other parts of the network and causes the highest number of transmissions. Additionally, the replication from source node continues on the high probable peers even the previous copies were transmitted on the better predictable neighbors than the current. In this paper, we have proposed a novel routing method called as the adaptive threshold based locking method that maintains the contemporary status of the node based on its activity in the network. We have used the adaptive status measuring metrics such as transmit factor, drop factor and hop away count. Moreover, a threshold based locking method has been introduced to control the diffusion of messages. We have performed the comparison of existing and proposed routing methods with real time mobility traces. The proposed strategy has bolstered the delivery ratio and minimizes hop count, end-to-end delay and number of transmission. [ABSTRACT FROM AUTHOR]

Delay Tolerant Networks (DTNs) provide message delivery services to users via intermittently connected nodes. In DTNs, routing is one of the most challenging issues since end-to-end connectivity between nodes may not be available most of the time. Although many routing protocols for DTNs have been proposed, they do not achieve satisfactory performance, since they exploit only some of the network characteristics. In this paper, we present a new DTN routing protocol, called the Link Contact Duration-based Routing Protocol (LCD). Like existing protocols, LCD uses the disconnect duration of a link between two nodes to find the routing path with the shortest end-to-end delay. In addition, LCD uses the contact duration of a link and the number of buffered messages to deliver as many messages as possible in a short time. Our simulation results show that LCD has better performance than existing DTN routing protocols. [ABSTRACT FROM AUTHOR]

Vehicular networks are popular in recent years to provide low cost communication medium during mobility. Vehicular Delay Tolerant Networks (DTNs) are one of the major categories of emerging technology. DTNs work on carry and forward mechanism to deliver data to the destination. The network performance gets severely affected due to reluctance shown by selfish nodes where few nodes show no interest in forwarding others data due to lack of any personal profit. The proposed mechanism is based on coalition game theory and discusses about incentive based mechanism which provides incentive to nodes which are forwarding data to forward to destination and motivates other vehicles in the network to participate in coalition to forward data. This scheme not only encourages other selfish nodes to forward their private data and other nodes' public data as early as possible to destination but also increases reliability in the network as more nodes show their interest in selected routing protocol. The proposed scheme outperforms in overall benefit earned by individual node and whole coalition, and increases mutual cooperation which improves availability of data in the network. [ABSTRACT FROM AUTHOR]

In recent years, Wireless Sensor Network (WSN) has been used for several applications and various roles like information gathering, monitoring data, transmitting data, etc. However, the key drawback behind this WSN is energy consumption. In WSN, some nodes have been consumed more energy because of malicious events like replication nodes. So, the replication node must be predicted in the initial stage to avoid packet drop and minimize energy consumption. So, this current research proposed a novel Whale-based Node Identity Verification (WbNIV) for detecting replication nodes in the Mobile Wireless Sensor Network. Moreover, the fitness function of the whale is used to identify each node's energy level and for exact replication node detection. Initially, the required numbers of nodes are designed then the details of a node are stored in WbNIV memory. During the monitoring and prediction process, the replication node in the WSN is identified by analyzing the details and behavior of the node. Finally, the proposed WbNIV has gained 98.89% replication node prediction accuracy, recorded the maximum packet drop as 12.8%, and reduced communication delay to 3 s, which is relatively better than the existing models. Thus, it has reduced power consumption up to 30% compared to the existing models. It has also improved the detection accuracy up to 5% than the compared models and has reduced the packet drop up to 10% compared to conventional approaches. [ABSTRACT FROM AUTHOR]

Although centrality is widely used to differentiate the importance of nodes for social-aware routing in mobile opportunistic networks (MONs), it is destination-agnostic since such metrics are usually measured without destination information. To this end, we propose a destination-aware social routing scheme for MONs, namely DAS, which utilizes the destination-aware betweenness centrality (DBC) to choose the right nodes as relays given the specific destination node. During the process of message dissemination, the number of replicas for a message is calculated by the source and each relay independently in respond to the network condition in a dynamic manner. Therefore, DAS disseminates only a few message copies to ensure data delivery as well as reducing routing cost. We conduct extensive simulations using real trace data sets to show improved performance with low overhead in comparison with existing social-aware routing approaches in various scenarios. [ABSTRACT FROM AUTHOR]

Internet of things consist in the deployment of constrained and battery-powered devices with a radio interface. Most industrial applications require to respect strict reliability and delay constraints. Lossy links imply mechanisms to retransmit the packets to improve the reliability. However, transient faults (e.g. obstacles, interference) may also impact the reliability, and require to change the routes. In this article, we present cooperative storing mode (CoopStor), that detects the faults and triggers action before a packet is dropped. In particular, the packets are cooperatively stored in the network, until the routing protocol re-converges. The congested zone gradually increases to serve as a local storage facility. CoopStor relies on a selection of relay and leaf nodes to reduce the energy consumption while providing a low end-to-end delay in steady state. Our performance evaluation campaign highlights a reduction of packet drops and an improved energy-efficient data collection procedure. [ABSTRACT FROM AUTHOR]

In delay tolerant networks (DTNs), nodes have intermittent connectivity patterns due to various factors such as mobility, sparse network topology, and unpredictable movement patterns. In such networks, nodes store messages, carry them along as they move and forward them opportunistically whenever an encounter occurs. In many DTN applications, such as in disaster situations and remote regions with no communications infrastructure, we can envisage a network topology formed by the mobility and contact pattern of people carrying their mobile devices. The social behavior of people (nodes) in Spatio-temporal dimensions governs the formation of such a topology. To improve data dissemination in such networks, several works have proposed to utilize social-aware metrics for the selection of relays. However, existing routing protocols for DTNs may perform poorly in the scenarios in which nodes are localized in multiple small regions, and the topology is sparse such as in co-located villages in remote regions with no communication infrastructure. This work proposes a Cooperative mobile throwbox-based routing protocol (CMTR) for social-aware DTNs. In CMTR, static and mobile ThrowBoxes (TBs) are deployed to improve the efficiency of a DTN. The static and mobile TBs cooperatively relay data to enhance network efficiency. Performance evaluation via simulations in ONE simulator shows that CMTR improves the data delivery ratio, delays, and energy efficiency as compared to Epidemic routing and Bubble Rap routing schemes. [ABSTRACT FROM AUTHOR]

Vehicular delay tolerant networks (VDTNs) enable communications in sparse vehicular ad-hoc networks and other challenged environments where traditional networking approaches fail. We propose a VDTN routing scheme that combines the message deliver strategy of PRoPHET protocol, the message copy control strategy of Spray-and-Wait protocol and an enhanced buffer management scheme. In our proposal, the buffer management scheme is designed to improve certain network performance goals, namely, maximizing the average delivery ratio and minimizing the average delivery delay. Furthermore, we use computer simulations to show that the proposed routing scheme achieves better system performance than the existing baseline routing protocols. [ABSTRACT FROM AUTHOR]

Fault resilient routing is a typical issue for underwater wireless sensor networks ( UWSNs ) due to contact of underwater creatures, mobility of nodes and natural disaster. In the existing studies, most of the researchers introduced routing scheme for routing the packets towards the base station through a cluster head. However, these schemes use static or mobile nodes for deployment, but nodes move from its original position to another position and get stuck in a particular region due to ocean current, natural disaster and environmental interference. Therefore, this leads to high energy depletion, link failure, disjoint path and overloaded data. To resolve this issue, we have proposed fault resilient routing based on moth flame optimization ( MFO ) scheme for transferring the packets towards the base station through autonomous underwater vehicles ( AUVs ). In this scheme, AUVs is used instead of cluster head to avoid the reclustering, overloading problem and it also feasible for large scale networks. There may be a disjoint path issue, so we have deployed additional mobile nodes with the help of AUVs within the network. Further, a novel fitness function is integrated with the MFO scheme to overcome the link failure problem. The proposed scheme is applied to select the best forwarding node for transmitting the packets towards the nearest AUVs using multi-hop acoustic links. In UWSNs , AUVs is placed to move the packets towards the BS from lower level to upper level. Performance evaluation of proposed scheme shows better result in terms of fault resilient, residual energy, network lifetime, packet delivery ratio and convergence rate than the existing scheme under the different network scenario. [ABSTRACT FROM AUTHOR]

In the absence of Internet connectivity, a content-centric opportunistic network can be established by mobile human-held devices. However, to save battery, buffer, and bandwidth resources, device carriers may selfishly disable their delay-tolerant networking (DTN) application when communication is not desired. Consequently, the network performance will degrade as the majority of the data forwarding protocols for the DTNs are designed assuming cooperative relaying by nodes. To inculcate cooperation among the otherwise selfish communicating nodes, we propose an incentive-aware pricing game for interest-based social-aware forwarding in the DTNs. We formulate the pricing game between nodes as the Rubinstein Bargain model to enhance content distribution in DTNs. The communicating nodes decide the pricing and the cooperation level based on the following three parameters: (1) remaining battery level, (2) their social strength, and (3) message worth. Moreover, to enhance content distribution of large size messages in such networks, the proposed algorithm enables nodes to share information in a peer-to-peer fashion. Performance evaluation shows that the proposed algorithm effectively increases the distribution ratio of complete files, reduces their data delivery delays, and mitigates the selfish behavior of nodes. [ABSTRACT FROM AUTHOR]