Intermittently Connected Mobile Networks Research Articles

Resource Optimization Protocol Based on Multicommunity Model for Intermittently Connected Mobile Networks

Intermittently connected mobile networks (ICMNs) are kinds of delay-tolerant networks (DTNs) in which the topology of mobile network changes frequently, the network is sparse, and end-to-end connection is hard to establish. However, as nodes in DTNs may often have limited energy, the performance of the network will be inevitably affected. Particularly, the message delivery ratio will be decreased when some of the nodes are out of energy and unable to participate in relay process. In order to make effective use of resources, we take this into consideration and propose the social similarity and optimized resource (SSAOR) protocol. According to the position relationship between the source and the destination nodes, SSAOR uses two different strategies to determine the order of forwarding messages. If they belong to the same community, the source node forwards message, copies to the relay node with the shorter encounter interval and the higher social friendship rank similarity with destination nodes. Otherwise, the source node forwards message copies to the relay node with the higher weight “betweenness” similarity and the shorter waiting encounter time similarity with destination nodes. In addition, we propose a buffer management method for dynamically distributing message copies to reduce network overhead, due to the fact that only a small number of copies can be successfully delivered. Finally, the simulation results show that SSAOR achieves a higher delivery ratio and lower overhead ratio, compared to other protocols within resource-constrained network situations.

Impact of buffer size and TTL on DTN routing protocols in intermittently connected mobile networks

Delay-Tolerant Networks (DTNs) are kinds of networks where there does not exist any complete end-to-end route from source to destination. Such networks can also be referred to as Intermittently Connected Mobile Networks (ICMNs), which are featured by asymmetric data rates, large delay, limited resources and high error rates. In this network, size of buffer and Time-to-Live (TTL) for fixed number of nodes and message generation rates contribute to the network performance because of limited resources and short life span of a packet in the net-work. Therefore, investigating efficient routing for altering TTL and size of buffer is very important for overall network performance. This paper presents a performance analysis based on simulation of the impact of buffer size and TTL for several DTN routing protocols in ICMNs scenario. ONE, i.e., Opportunistic Network Environment is used to simulate the routing protocols considering three performance metrics: delivery ratio, mean latency and overhead ratio. Investigated results mention that Spray-and-Focus (SNF) routing exhibits the best performance for altering TTL and size of buffer than other DTN routing protocols, i.e., Epidemic, PRoPHET, PRoPHETv2, MaxProp, RAPID, and Binary-SNW in the considered performance metrics and simulation scenario.

Performance Analysis of Message Dissemination in ICMN under the Last-Create-First-Relay Scheme

With encounter-based communication introduced in intermittently connected mobile networks (ICMNs), the message dissemination in mobile Internet subscriber/publisher services can be augmented through near-distance communication of mobile nodes. Specifically, mobile nodes with Internet connectivity can help those without to obtain messages once stored and currently carried by the former. We model such a system, particularly considering the time-critical property of messages, the limited communication bandwidth, and the existence of multiple sources. Based on the model, we propose analytical methods for obtaining the performance of message delivery ratio and average delay under the 1-hop or the 2-hop relaying mode specified in this paper, respectively. Through extensive simulations, we validate the proposed methods and discuss system performance under different parameter settings and relaying schemes.

Privacy Preserving Bee Routing Protocol for Intermittently Connected Mobile Networks

The Intermittently Connected Mobile Networks (ICMN) is a disconnected mobile network where a complete connectivity never exists. More number of moving nodes makes them impenetrable genre which in turn makes the network intermittently connected. Detection of malicious node and routing is onerous due to its genre. In this paper, we put forward a secure routing that aids in detecting and preventing intrusion of malicious nodes. The routing process is made more adorable through Bee Colony Optimization (BCO). The amalgamation of BCO with authentication series leads a novel routing protocol named Privacy Preserving Bee Routing Protocol (PPBRP) which is highly secure. The degree of security is tested with malicious nodes in the network to prove that the proposed PPBRP ensures secure routing.

On the Performance of Delay-Tolerant Routing Protocols in Intermittently Connected Mobile Networks

Delay-Tolerant Networks are used to enable communication in challenging environments where nodes are intermittently connected, and an end-to-end path does not exist all the time between source and destination, e.g., Intermittently Connected Mobile Networks (ICMNs). Therefore, network environments, where the nodes are characterized by opportunistic connectivity, are appropriately modeled as Delay-Tolerant Networks (DTNs). In this paper, we have investigated the performance of DTN routing protocols, namely Epidemic, PRoPHET, and Spray-and-Wait (Binary version) in an ICMN scenario. Their performances are analyzed in terms of delivery probability, average latency, and overhead ratio of varying message generation rates and number of mobile nodes, respectively. In addition, the impacts of varying buffer size and Time-to-Live (TTL) on their performances are investigated. For evaluating these performance metrics, we have used Opportunistic Network Environment (ONE) simulator as the simulation tool. The outcome of this work shows that for the ICMN scenario, the best DTN routing technique is Binary Spray-and-Wait, whereas Epidemic routing exhibits the worst performance in terms of all the metrics considered here.

Capacity and delay-throughput tradeoff in ICMNs with Poisson contact process

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 proces...

S-SPRAY ROUTING PROTOCOL FOR INTERMITTENTLY CONNECTED MOBILE NETWORKS

The Intermittently Connected Mobile Networks (ICMN) is a disconnected mobile network where a complete connectivity never exists. The intermittent connectivity is due to the dense nature of the network. The dense nature is mainly due to the high mobility of the nodes in the network. Routing in such a sparse network is arduous. Due to the disconnected attribute of the network, the encounter of the suspicious nodes in the network also remains a tedious task. In this paper, we put forward a secure routing that aids in detecting and preventing intrusion of malicious nodes. The routing process is made adorable through Spray and Wait (SNW). Since ICMN is prompt to higher delays certain authentication series are used to enable secure communication within the network. The amalgamation of SNW with authentication series leads a novel routing protocol named S-Spray (Secured-Spray) which is highly secure.

NER-DRP: Dissemination-based Routing Protocol with Network-layer Error Control for Intermittently Connected Mobile Networks

Reliable transmission in Intermittently Connected Mobile Networks (ICMNs) is a challenging work because the effective and reliable connection between the source and the destination can not be sustained. To reliably hand over data packets to the destination, many dissemination-based routing protocols are proposed. Dissemination-based routing protocols assure nodes including intermediate nodes and destinations have more chances to receive packets, which will increase the probability that the packets can be correctly received by the destination. However, the existing error recovery mechanisms in network layer use the simple CRC to check the data packets independently, and discard the error packets even if one correct packet can be obtained from more than one partly error packets. In this paper, first we propose a novel Network layer Error Recovery method (abbreviated as NER) based on Forward Error Correction (FEC). NER divides a data packet into Reed Solomon (RS) blocks and insert redundancy to each block. So the intermediate nodes and destinations can recover a correct data packet from multiple partially error copies of the same packet. Then we propose a novel routing protocol named NER-DRP based on the Epidemic routing and NER, which can improve the performance of ICMNs in terms of delivery ratio, end-to-end delay and count of hops.

Optimized Replication Strategy for Intermittently Connected Mobile Networks

Intermittently Connected Mobile Networks (ICMNs) are wireless networks where due to mobility of nodes and lack of connectivity, there may be disconnection among the nodes. Hence, the routing path from source to destination is not always available. In this case, Mobile Ad-hoc Network (MANET) protocols will not be utilized. In these networks, messages are to be flooded or multiple replications are needed to withstand the maximum delay and achieve the high delivery ratio. But multiple replication based protocols result in increased network overhead and high resource consumption because of uncontrolled replication. In this paper, the authors introduce a new simple scheme which applies knapsack policy based replication strategy in replicating the messages. The number of replication is reduced by appropriately selecting only limited messages based on the number of duplications of its own and its size. The messages are selected for forwarding to relay node based on the goodness of the relay node in contacting the destination and the buffer size of the relay node. Therefore, only limited messages will be replicated in the network and it will reduce the network overhead, resource consumption, delivery delay and increases the delivery ratio.

Performance of Opportunistic Epidemic Routing on Edge-Markovian Dynamic Graphs

Connectivity patterns in intermittently-connected mobile networks (ICMN) can be modeled as edge-Markovian dynamic graphs. We propose a new model for epidemic propagation on such graphs and calculate a closed-form expression that links the best achievable delivery ratio to common ICMN parameters such as message size, maximum tolerated delay, and link lifetime. These theoretical results are compared to those obtained by replaying a real-life contact trace.