Evaluating Mobility Pattern Space Routing for DTNs

Because a delay tolerant network (DTN) can often be partitioned, the problem of routing is very challenging. However, routing benefits considerably if one can take advantage of knowledge concerning node mobility. This paper addresses this problem with a generic algorithm based on the use of a high-dimensional Euclidean space, that we call MobySpace, constructed upon nodes' mobility patterns. We provide here an analysis and the large scale evaluation of this routing scheme in the context of ambient networking by replaying real mobility traces. The specific MobySpace evaluated is based on the frequency of visit of nodes for each possible location. We show that the MobySpace can achieve good performance compared to that of the other algorithms we implemented, especially when we perform routing on the nodes that have a high connection time. We determine that the degree of homogeneity of mobility patterns of nodes has a high impact on routing. And finally, we study the ability of nodes to learn their own mobility patterns.Comment: IEEE INFOCOM 2006 preprin

Pervasive intelligent routing in content centric delay tolerant networks

This paper introduces a Swarm-Intelligence based Routing protocol (SIR) that aims to efficiently route information in content centric Delay Tolerant Networks (CCDTN) also dubbed pocket switched networks. First, this paper formalizes the notion of optimal path in CCDTN and introduces an original and efficient algorithm to process these paths in dynamic graphs. The properties and some invariant features of these optimal paths are analyzed and derived from several real traces. Then, this paper shows how optimal path in CCDTN can be found and used from a fully distributed swarm-intelligence based approach of which the global intelligent behavior (i.e. shortest path discovery and use) emerges from simple peer to peer interactions applied during opportunistic contacts. This leads to the definition of the SIR routing protocol of which the consistency, efficiency and performances are demonstrated from intensive representative simulations

Opportunistic routing and network coding in multi-hop wireless mesh networks

The rapid advancements in communication and networking technologies boost the capacity of wireless networks. Multi-hop wireless networks are extremely exciting and rapidly developing areas and have been receiving an increasing amount of attention by researchers. Due to the limited transmission range of the nodes, end-to-end nodes may situate beyond direct radio transmission ranges. Intermediate nodes are required to forward data in order to enable the communication between nodes that are far apart. Routing in such networks is a critical issue. Opportunistic routing has been proposed to increase the network performance by utilizing the broadcast nature of wireless media. Unlike traditional routing, the forwarder in opportunistic routing broadcasts date packets before the selection of the next hop. Therefore, opportunistic routing can consider multiple downstream nodes as potential candidate nodes to forward data packets instead of using a dedicated next hop. Instead of simply forwarding received packets, network coding allows intermediate nodes to combine all received packets into one or more coded packets. It can further improve network throughput by increasing the transmission robustness and efficiency. In this dissertation, we will study the fundamental components, related issues and associated challenges about opportunistic routing and network coding in multi-hop wireless networks. Firstly, we focus on the performance analysis of opportunistic routing by the Discrete Time Markov Chain (DTMC). Our study demonstrates how to map packet transmissions in the network with state transitions in a Markov chain. We will consider pipelined data transfer and evaluate opportunistic routing in different wireless networks in terms of expected number of transmissions and time slots. Secondly, we will propose a regional forwarding schedule to optimize the coordination of opportunistic routing. In our coordination algorithm, the forwarding schedule is limited to the range of the transmitting node rather than among the entire set of forwarders. With such an algorithm, our proposal can increase the throughput by deeper pipelined transmissions. Thirdly, we will propose a mechanism to support TCP with opportunistic routing and network coding, which are rarely incorporated with TCP because the frequent occurrences of out-of-order arrivals in opportunistic routing and long decoding delay in network coding overpower TCP congestion control. Our solution completes the control feedback loop of TCP by creating a bridge between the sender and the receiver. The simulation result shows that our protocol significantly outperforms TCP/IP in terms of network throughput in different topologies of wireless networks

A stateless opportunistic routing protocol for underwater sensor networks

Routing packets in Underwater Sensor Networks (UWSNs) face different challenges, the most notable of which is perhaps how to deal with void communication areas. While this issue is not addressed in some underwater routing protocols, there exist some partially state-full protocols which can guarantee the delivery of packets using excessive communication overhead. However, there is no fully stateless underwater routing protocol, to the best of our knowledge, which can detect and bypass trapped nodes. A trapped node is a node which only leads packets to arrive finally at a void node. In this paper, we propose a Stateless Opportunistic Routing Protocol (SORP), in which the void and trapped nodes are locally detected in the different area of network topology to be excluded during the routing phase using a passive participation approach. SORP also uses a novel scheme to employ an adaptive forwarding area which can be resized and replaced according to the local density and placement of the candidate forwarding nodes to enhance the energy efficiency and reliability. We also make a theoretical analysis on the routing performance in case of considering the shadow zone and variable propagation delays. The results of our extensive simulation study indicate that SORP outperforms other protocols regarding the routing performance metrics