2,616 research outputs found
Cross-layer Balanced and Reliable Opportunistic Routing Algorithm for Mobile Ad Hoc Networks
For improving the efficiency and the reliability of the opportunistic routing
algorithm, in this paper, we propose the cross-layer and reliable opportunistic
routing algorithm (CBRT) for Mobile Ad Hoc Networks, which introduces the
improved efficiency fuzzy logic and humoral regulation inspired topology
control into the opportunistic routing algorithm. In CBRT, the inputs of the
fuzzy logic system are the relative variance (rv) of the metrics rather than
the values of the metrics, which reduces the number of fuzzy rules
dramatically. Moreover, the number of fuzzy rules does not increase when the
number of inputs increases. For reducing the control cost, in CBRT, the node
degree in the candidate relays set is a range rather than a constant number.
The nodes are divided into different categories based on their node degree in
the candidate relays set. The nodes adjust their transmission range based on
which categories that they belong to. Additionally, for investigating the
effection of the node mobility on routing performance, we propose a link
lifetime prediction algorithm which takes both the moving speed and moving
direction into account. In CBRT, the source node determines the relaying
priorities of the relaying nodes based on their utilities. The relaying node
which the utility is large will have high priority to relay the data packet. By
these innovations, the network performance in CBRT is much better than that in
ExOR, however, the computation complexity is not increased in CBRT.Comment: 14 pages, 17 figures, 31 formulas, IEEE Sensors Journal, 201
Stuck in Traffic (SiT) Attacks: A Framework for Identifying Stealthy Attacks that Cause Traffic Congestion
Recent advances in wireless technologies have enabled many new applications
in Intelligent Transportation Systems (ITS) such as collision avoidance,
cooperative driving, congestion avoidance, and traffic optimization. Due to the
vulnerable nature of wireless communication against interference and
intentional jamming, ITS face new challenges to ensure the reliability and the
safety of the overall system. In this paper, we expose a class of stealthy
attacks -- Stuck in Traffic (SiT) attacks -- that aim to cause congestion by
exploiting how drivers make decisions based on smart traffic signs. An attacker
mounting a SiT attack solves a Markov Decision Process problem to find
optimal/suboptimal attack policies in which he/she interferes with a
well-chosen subset of signals that are based on the state of the system. We
apply Approximate Policy Iteration (API) algorithms to derive potent attack
policies. We evaluate their performance on a number of systems and compare them
to other attack policies including random, myopic and DoS attack policies. The
generated policies, albeit suboptimal, are shown to significantly outperform
other attack policies as they maximize the expected cumulative reward from the
standpoint of the attacker
Towards Optimal Distributed Node Scheduling in a Multihop Wireless Network through Local Voting
In a multihop wireless network, it is crucial but challenging to schedule
transmissions in an efficient and fair manner. In this paper, a novel
distributed node scheduling algorithm, called Local Voting, is proposed. This
algorithm tries to semi-equalize the load (defined as the ratio of the queue
length over the number of allocated slots) through slot reallocation based on
local information exchange. The algorithm stems from the finding that the
shortest delivery time or delay is obtained when the load is semi-equalized
throughout the network. In addition, we prove that, with Local Voting, the
network system converges asymptotically towards the optimal scheduling.
Moreover, through extensive simulations, the performance of Local Voting is
further investigated in comparison with several representative scheduling
algorithms from the literature. Simulation results show that the proposed
algorithm achieves better performance than the other distributed algorithms in
terms of average delay, maximum delay, and fairness. Despite being distributed,
the performance of Local Voting is also found to be very close to a centralized
algorithm that is deemed to have the optimal performance
Applications of Geometric Algorithms to Reduce Interference in Wireless Mesh Network
In wireless mesh networks such as WLAN (IEEE 802.11s) or WMAN (IEEE 802.11),
each node should help to relay packets of neighboring nodes toward gateway
using multi-hop routing mechanisms. Wireless mesh networks usually intensively
deploy mesh nodes to deal with the problem of dead spot communication. However,
the higher density of nodes deployed, the higher radio interference occurred.
This causes significant degradation of system performance. In this paper, we
first convert network problems into geometry problems in graph theory, and then
solve the interference problem by geometric algorithms. We first define line
intersection in a graph to reflect radio interference problem in a wireless
mesh network. We then use plan sweep algorithm to find intersection lines, if
any; employ Voronoi diagram algorithm to delimit the regions among nodes; use
Delaunay Triangulation algorithm to reconstruct the graph in order to minimize
the interference among nodes. Finally, we use standard deviation to prune off
those longer links (higher interference links) to have a further enhancement.
The proposed hybrid solution is proved to be able to significantly reduce
interference in a wireless mesh network in O(n log n) time complexity.Comment: 24 Pages, JGraph-Hoc Journal 201
Multipath optimized link state routing for mobile ad hoc networks
International audienceMultipath routing protocols for Mobile Ad hoc NETwork (MANET) address the problem of scalability, security (confidentiality and integrity), lifetime of networks, instability of wireless transmissions, and their adaptation to applications. Our protocol, called MP-OLSR (MultiPath OLSR), is a multipath routing protocol based on OLSR. The Multipath Dijkstra Algorithm is proposed to obtain multiple paths. The algorithm gains great flexibility and extensibility by employing different link metrics and cost functions. In addition, route recovery and loop detection are implemented in MP-OLSR in order to improve quality of service regarding OLSR. The backward compatibility with OLSR based on IP source routing is also studied. Simulation based on Qualnet simulator is performed in different scenarios. A testbed is also set up to validate the protocol in real world. The results reveal that MP-OLSR is suitable for mobile, large and dense networks with large traffic, and could satisfy critical multimedia applications with high on time constraints
Performance Assessment of Aggregation and Deaggregation Algorithms in Vehicular Delay-Tolerant Networks
Vehicular Delay-Tolerant Networks (VDTNs) are a new approach for vehicular
communications where vehicles cooperate with each other, acting as the
communication infrastructure, to provide low-cost asynchronous opportunistic
communications. These communication technologies assume variable delays
and bandwidth constraints characterized by a non-transmission control protocol/
internet protocol architecture but interacting with it at the edge of the
network.
VDTNs are based on the principle of asynchronous communications, bundleoriented
communication from the DTN architecture, employing a store-carryand-
forward routing paradigm. In this sense, VDTNs should use the tight network
resources optimizing each opportunistic contact among nodes.
At the ingress edge nodes, incoming IP Packets (datagrams) are assembled
into large data packets, called bundles. The bundle aggregation process plays
an important role on the performance of VDTN applications. Then, this paper
presents three aggregation algorithms based on time, bundle size, and a hybrid
solution with combination of both. Furthermore, the following four aggregation
schemes with quality of service (QoS) support are proposed: 1) single-class bundle
with N = M, 2) composite-class bundle with N = M, 3) single-class bundle
with N > M, and 4) composite-class bundle with N > M, where N is the number
of classes of incoming packets and M is the number of priorities supported
by the VDTN core network. The proposed mechanisms were evaluated through
a laboratory testbed, called VDTN@Lab. The adaptive hybrid approach and the
composite-class schemes present the best performance for different types of
traffic load and best priorities distribution, respectively
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