Routing in Delay-tolerant network Based on Nodes’ Sociality

Due to the dynamic change of the opportunistic network topology and the lack of stable information transmission paths between nodes, the traditional topology-based routing algorithm cannot achieve the desired routing performance. To address of this problem, this paper proposes a routing algorithm based on trajectory prediction (RATP). The routing protocol based on trajectory prediction can efficiently and quickly adapt to the network link quality instability and the dynamic changes of network topology. RATP algorithm constructs a node mobility model by analyzing the historical mobility characteristics of the nodes. According to the node prediction information, the metric value of the candidate node is calculated, and the node with the smaller metric value is selected as the data forwarding node, which can effectively reduce the packet loss rate and avoids excessive consumption. Simulation results show that compared with other algorithms, the proposed algorithm has higher data delivery ratio, and end-to-end data delay and routing overhead are significantly reduced.

We consider the problem of routing in a delay tolerant network (DTN) in the presence of path failures. Previous work on DTN routing has focused on using precisely known network dynamics, which does not account for message losses due to link failures, buffer overruns, path selection errors, unscheduled delays, or other problems. We show how to split, replicate, and erasure code message fragments over multiple delivery paths to optimize the probability of successful message delivery. We provide a formulation of this problem and solve it for two cases: a 0/1 (Bernoulli) path delivery model where messages are either fully lost or delivered, and a Gaussian path delivery model where only a fraction of a message may be delivered. Ideas from the modern portfolio theory literature are borrowed to solve the underlying optimization problem. Our approach is directly relevant to solving similar problems that arise in replica placement in distributed file systems and virtual node placement in DHTs. In three different simulated DTN scenarios covering a wide range of applications, we show the effectiveness of our approach in handling failures.

In certain extreme environments where infrastructure such as base stations is absent, connections between nodes can be intermittent. Traditional networks struggle to function in these conditions. Delay Tolerant Network (DTN) are a network architecture designed for such scenarios. Utilizing Unmanned Aerial Vehicle (UAV) as nodes within DTN can enhance the network’s transmission capabilities and compensate for the deficiencies of ground nodes. However, previous routing methods have shortcomings. Given the high speed and greater freedom of movement of UAVs compared to ground nodes, the network topology is subject to constant and significant change. Traditional routing methods, which typically rely on predetermined rules for selecting forwarding nodes, struggle to adapt to such variations. This paper introduces Graph Neural Network (GNN) into routing decisions for DTN to learn network structural information and assist with routing decisions. In this paper, we first model the routing problem within DTN, accounting for the dynamic changes in network topology and limited resources. Subsequently, we propose a GNN-based dynamic routing method. This method utilizes a graph neural network model that takes as input the feature s of nodes at the current moment and the network’s connectivity information to generate optimal forwarding nodes for each data packet. The proposed method has been implemented in the Opportunistic Networking Environment (ONE) simulator. Experimental results indicate that our method achieves higher delivery ratio, lower latency, and reduced overhead compared to traditional methods.

The framework of Delay Tolerant Networks (DTNs) has recently received an extensive attention and widely implemented, ranging from Wireless Sensor Networks (WSNs) to Interplanetary Networks. It has been applied in military communication, scientific research and exploration. Due to the characteristic of long delay, intermittent disruption, limitation of buffer space and energy, the traditional routing algorithms in the Internet do not perform well in DTNs. Since most of the existing DTN routing algorithms are based on the replication mechanism to achieve the high delivery ratio. In this paper, we propose an asymmetric spray algorithm based on the limited number of replication with the consideration of utility metric. In addition, we also design an adaptive replication function to optimize the dropped messages due to the insufficient encounter duration. Simulation results show the effectiveness of our asymmetric spray approach. In combination with the other designed functions, our proposed algorithm achieve a better performance than the state of the art algorithms.

Majority of the existing Delay Tolerant Network (DTN) routing protocols, attempt to minimize one of the popular DTN routing indices, i.e. message delay, forwarding count and storage. However, for many DTN applications such as distributing commercial content, targeting the best performance for one index and compromising the others is insufficient. A more practical solution would be to strike a balance between multiple of these indices. Gain Dissemination Protocol (GDP) is one of the protocols which targets this aim by introducing a gain concept which tries reach a maximum gain of delivery by keeping the balance between the value achieved via delivering the packet to the destination and the forwarding cost involved with that. In this paper, we focus on characterizing the GDP protocol in the scope of mobility. We also propose an upper bound for gain in multicast routing problem, i.e. the Union of Unicast Benchmark (UUB) and compare the performance of a few DTN routing protocols with the former. This eventually reveals the performance scope of a potential gain-aware DTN dissemination protocol.

It is a fast and simple way to run a Delay Tolerant Network (DTN) by mobile terminals in an urban environment, therefore DTN currently plays an important role as a network for Internet of Things (IoT). The network metrics are important for performance of DTN based communication systems. Because moving characteristics in urban environments are different from other challenging network environments, then the routing method is also different in various environments. In general, routing algorithm decides the DTN performance, so it cannot release potential performance with traditional routing algorithms in cities. In this paper, we propose a routing algorithm for urban areas, named Forward Routing based Distance Variation (FRDV), and we designed such approach according to human moving characteristics. FRDV comprises two stages which include selecting relay node and messages transmission decision. At the first stage, FRDV select a relay node depend on sending activity which depends on delivery frequency of nodes. During the short encounter time, the nodes selectively sent messages to the relay node based on moving status of nodes at the second stage. The simulation results suggest that FRDV outperforms than classical algorithms such as Epidemic, Prophet, Direct Delivery and First Contact algorithms in urban environments.

Due to dynamic changes in network topology and constant changes in links between satellites, the routing paths calculated by the traditional shortest multipath routing algorithm are not updated in time, resulting in that the problematic paths are still transmitting data, so a large number of problems such as packet loss and service failure exist in the network. This paper designs a multipath routing algorithm for the satellite network topology which changes frequently, constrained multipath routing algorithm (CMRA). By calculating all feasible path of the entire network topology, CMRA will choose the multiple paths which satisfy the constraint conditions. After that, it will choose the lowest cost value of these paths. Repeatedly performing these operations, select multiple high-quality paths which satisfy the constraint conditions for traffic. Simulation results show that compared with the traditional shortest multipath routing algorithm and single path routing algorithm, the proposed routing algorithm is better in packet loss rate and average time delay.

Networks that lack continuous connectivity among their nodes due to node mobility, limited data storage space and constrained power sources are called Delay Tolerant Networks (DTNs). DTN nodes store and carry the data packets until they come into the communication range of each other. In recent years several protocols have been developed specifically for routing in DTNs. These protocols vary in number of copies they use and the kind and amount of knowledge they use to guide the packets to their destinations. Remaining energy level, average latency, overhead ratio and delivery ratio are some of the performance metrics used to measure the performance of these protocols. The existing protocols are good in some of these metrics but not all of them. There is always a trade-off between different performance metrics. In this paper we have proposed a Hybrid protocol utilizing advantages of two protocols namely Epidemic and Probabilistic Routing. The performance is discussed and compared of these protocols with our Hybrid strategy in Opportunistic Network Environment tool.

Delay tolerant networks (DTNs) are wireless networks in which an end-to-end path for a given node pair can never exist for an extended period. It has been reported as a viable approach in launching multiple message replicas in order to increase message delivery ratio and reduce message delivery delay. This advantage, nonetheless, is at the expense of taking more buffer space at each node. The combination of custody and replication entails high buffer and bandwidth overhead. This paper investigates a new buffer management architecture for epidemic routing in DTNs, which helps each node to make a decision on which message should be forwarded or dropped. The proposed buffer management architecture is characterized by a suite of novel functional modules, including Summary Vector Exchange Module (SVEM), Networks State Estimation Module (NSEM), and Utility Calculation Module (UCM). Extensive simulation results show that the proposed buffer management architecture can achieve superb performance against its counterparts in terms of delivery ratio and delivery delay.KeywordsRoutingBuffer management

There is a growing need for secure and robust networks that function in austere environments or with nodes that have limited resources. The prime example is Delay Tolerant Networks that have military, first response, infrastructure failure and vehicle applications. This class of networks requires the modification of traditional routing and security protocols, such as TCP/IP or the use of certificate revocation servers, to effectively transmit a message from source to destination in a secure manner. There are multiple trust and routing schemes proposed for use in Delay Tolerant Networks. Here, we show how trust, usually defined in the context of network science, can be utilized for routing in Delay Tolerant Networks in which the fundamental challenge is balancing energy, delivery rate, delivery delay and security. Trust is a cornerstone of our approach to address this challenge. We propose a Trust Based Secure Routing Protocol, in which forwarding decisions are based on nodes trust, expected destination meeting time and the number of already created copies of the message.

ExMin: A routing metric for novel opportunity gain in Delay Tolerant Networks

Anycast routing is very useful for many applications such as resource discovery in delay tolerant networks (DTNs). In this paper, based on a new DTN model, we first analyze the any-cast semantics for DTNs. Then we present a novel metric named EMDDA (expected multi-destination delay for anycast) and a corresponding routing algorithm for anycast routing in DTNs. Extensive simulation results show that the proposed EMDDA routing scheme can effectively improve the efficiency of anycast routing in DTNs. It outperforms another algorithm, minimum expected delay (MED) algorithm, by 11.3% on average in term of routing delays and by 19.2% in term of average max queue length.

Biologists have long shown that the mobility patterns of many foraging animals and insects are similar to Levy walks and Levy walks are an optimal search strategy when target objects (i.e., food sources) are sparse and their locations are not known in advance. In this paper, we apply Levy walk patterns to routing in delay tolerant networks (DTN). In DTNs, message forwarding nodes often do not have full information about the whereabout of message destinations. Using the optimality property of Levy walks, we devise two styles of routing strategies. One is an active strategy using message ferries (MF) where the movement of MFs can be controlled to have a Levy walk pattern in order for them to maximize the opportunity of meeting the destinations and the other is a passive strategy in which the movement of nodes cannot be controlled, but messages are forwarded in such a manner that their forwarding patterns mimic the Levy walk patterns. We show through simulation that (1) both strategies are very effective when knowledge about destinations (i.e., contact history, trajectory or locations of destinations) is highly limited and (2) they complement existing utility-based routing which excels when such knowledge is available.

Due to the unstable network topology of Delay Tolerant Networks (DTNs), multi-copy routing is often used to increase the reliability of message delivery. However, this routing approach suffers from high buffer and bandwidth overhead. While much work has been done in the design of forwarding algorithms, little work has focused on studying forwarding under the presence of resource constraints such as short contact durations and small buffers. In this paper, we investigate a multi-copy routing strategy and a buffer management policy that maximize the delivery rate in DTNs. We consider a realistic DTN environment with resource constraints, heterogeneous node mobility, and varied message sizes. There are three key issues in DTN routing: (1) to which next hop relay node should messages be replicated, (2) in which order should messages be replicated, and (3) which messages should be dropped first when the buffer is full. We propose to forward a message to a neighboring node that has both a stronger social tie with the destination and a smaller or similar queue length. This aims to reduce traffic at highly connected network nodes, avoiding frequent message drops which compromise the delivery ratio. For the second and third issue, we develop a utility function using global network information to compute per-packet delivery rate utility. Messages are then scheduled and dropped according to their utility values. Extensive simulation results based on the real-world San Francisco cab trace show that our proposed scheme can achieve a delivery rate of up to 22% higher than existing schemes, while still maintaining a comparable average delivery delay. Furthermore, our scheme distributes the network loads more evenly, with the top 10% of network nodes handling only 24% of the forwardings.

SummaryIn Delay Tolerant Networks (DTNs), mobile nodes exploit encounter chances to transmit data via the established opportunistic link between encounter nodes. The transmission capacity between two encounter nodes is constrained by the duration of opportunistic links. How to transmit data efficiently is one of the fundamental and most important issues in DTNs. Recently, Random Linear Network Coding (RLNC) is proposed as a promising approach to improve data transmission efficiency in DTNs. To facilitate the development of deployment of RLNC based routing protocols, it is imperative to quantify the performance gain brought by RLNC in a rigorous and systematic way. In this paper, we develop an analytical model to evaluate the data transmission performance of RLNC based epidemic routing in DTNs. In the model, we consider that multiple unicast communication sessions compete for limited \capacity. Numerical results validate the effectiveness of our analytical model and demonstrate the significant performance improvement for data transmission in DTNs brought by RLNC. Our work of this paper provides a general tool for performance evaluation and useful guidelines for designing RLNC based routing protocols in DTNs. Copyright © 2015 John Wiley & Sons, Ltd.