258 research outputs found
Equational Reasonings in Wireless Network Gossip Protocols
Gossip protocols have been proposed as a robust and efficient method for
disseminating information throughout large-scale networks. In this paper, we
propose a compositional analysis technique to study formal probabilistic models
of gossip protocols expressed in a simple probabilistic timed process calculus
for wireless sensor networks. We equip the calculus with a simulation theory to
compare probabilistic protocols that have similar behaviour up to a certain
tolerance. The theory is used to prove a number of algebraic laws which
revealed to be very effective to estimate the performances of gossip networks,
with and without communication collisions, and randomised gossip networks. Our
simulation theory is an asymmetric variant of the weak bisimulation metric that
maintains most of the properties of the original definition. However, our
asymmetric version is particularly suitable to reason on protocols in which the
systems under consideration are not approximately equivalent, as in the case of
gossip protocols
ASUMAN: Age Sense Updating Multiple Access in Networks
We consider a fully-connected wireless gossip network which consists of a
source and receiver nodes. The source updates itself with a Poisson process
and also sends updates to the nodes as Poisson arrivals. Upon receiving the
updates, the nodes update their knowledge about the source. The nodes gossip
the data among themselves in the form of Poisson arrivals to disperse their
knowledge about the source. The total gossiping rate is bounded by a
constraint. The goal of the network is to be as timely as possible with the
source. In this work, we propose ASUMAN, a distributed opportunistic gossiping
scheme, where after each time the source updates itself, each node waits for a
time proportional to its current age and broadcasts a signal to the other nodes
of the network. This allows the nodes in the network which have higher age to
remain silent and only the low-age nodes to gossip, thus utilizing a
significant portion of the constrained total gossip rate. We calculate the
average age for a typical node in such a network with symmetric settings and
show that the theoretical upper bound on the age scales as . ASUMAN, with
an average age of , offers significant gains compared to a system where
the nodes just gossip blindly with a fixed update rate in which case the age
scales as
Analysis of multi-resolution data aggregation using push-assisted random walks in mobile ad-hoc network (MANET)
ABSTRACT Analysis of Multi-Resolution Data Aggregation using Push-assisted Random Walks in Mobile Ad-hoc Networks (MANETs) Sowmya Srinivasapura Devaraja Data Aggregation in Mobile Ad-hoc Network (MANET) has proven challenging because of changing topology. Structure-based models like tree-based, cluster-based and chain-based have high maintenance cost. In earlier works, different forms of biased random walks have been verified to be effective without need for structure maintenance. The key idea in the protocol was to use one or more tokens that are circulated using biased random walks to effectively compute the data aggregation. One such protocol is EZ-AG that uses Push-assisted Self-Repelling Random Walks . A self-repelling random walk of a token on a graph is one in which at each step, the token moves to a neighbor that has been visited least often. While self-repelling random walks visit all nodes in the network much faster than plain random walks, they tend to slow down when most of the nodes are already visited. It\u27s verified that a single step push phase at each node can significantly speed up the aggregation and eliminate the slow down. Results have been verified that EZ-AG achieves aggregation in only O (N) time and messages. When the network is quite large, obtaining only one aggregate may not be sufficient. It will be more useful to provide distance-sensitive multi-resolution aggregates of data. The contribution in this project is, we have analyzed the Hierarchical EZ-AG proposed to provide multi-resolution results. We show that aggregates for nearby regions are obtained at faster rate in comparison to the farther region. The idea is to introduce the tokens in the network at distinct levels, execute EZ-AG protocol and obtain localized data aggregation output at distinct levels. Existing techniques for hierarchical aggregations require O (N log5.4 (N)) messages. Hierarchical EZ-AG outperforms these techniques by aggregating with only O (N log (N)) messages. We evaluate the performance of hierarchical EZ-AG considering message overhead, token messages, number of aggregations at distinct levels, node speed and mobility. Our results are validated using simulations in network simulator, ns-3 for network ranging from 100 to 4000 nodes under different node speeds and mobility models
Math saves the forest
Wireless sensor networks are decentralised networks consisting of sensors that can detect events and transmit data to neighbouring sensors. Ideally, this data is eventually gathered in a central base station. Wireless sensor networks have many possible applications. For example, they can be used to detect gas leaks in houses or fires in a forest.\ud
In this report, we study data gathering in wireless sensor networks with the objective of minimising the time to send event data to the base station. We focus on sensors with a limited cache and take into account both node and transmission failures. We present two cache strategies and analyse the performance of these strategies for specific networks. For the case without node failures we give the expected arrival time of event data at the base station for both a line and a 2D grid network. For the case with node failures we study the expected arrival time on two-dimensional networks through simulation, as well as the influence of the broadcast range
EDDA: An Efficient Distributed Data Replication Algorithm in VANETs
Efficient data dissemination in vehicular ad hoc networks (VANETs) is a challenging issue due to the dynamic nature of the network. To improve the performance of data dissemination, we study distributed data replication algorithms in VANETs for exchanging information and computing in an arbitrarily-connected network of vehicle nodes. To achieve low dissemination delay and improve the network performance, we control the number of message copies that can be disseminated in the network and then propose an efficient distributed data replication algorithm (EDDA). The key idea is to let the data carrier distribute the data dissemination tasks to multiple nodes to speed up the dissemination process. We calculate the number of communication stages for the network to enter into a balanced status and show that the proposed distributed algorithm can converge to a consensus in a small number of communication stages. Most of the theoretical results described in this paper are to study the complexity of network convergence. The lower bound and upper bound are also provided in the analysis of the algorithm. Simulation results show that the proposed EDDA can efficiently disseminate messages to vehicles in a specific area with low dissemination delay and system overhead
On the Impact of Geometry on Ad Hoc Communication in Wireless Networks
In this work we address the question how important is the knowledge of
geometric location and network density to the efficiency of (distributed)
wireless communication in ad hoc networks. We study fundamental communication
task of broadcast and develop well-scalable, randomized algorithms that do not
rely on GPS information, and which efficiency formulas do not depend on how
dense the geometric network is. We consider two settings: with and without
spontaneous wake-up of nodes. In the former setting, in which all nodes start
the protocol at the same time, our algorithm accomplishes broadcast in rounds under the SINR model, with high probability (whp), where
is the diameter of the communication graph and is the number of
stations. In the latter setting, in which only the source node containing the
original message is active in the beginning, we develop a slightly slower
algorithm working in rounds whp. Both algorithms are based on a
novel distributed coloring method, which is of independent interest and
potential applicability to other communication tasks under the SINR wireless
model
ENERGY CONSERVATION FOR WIRELESS AD HOC ROUTING
Self-configuring wireless ad hoc networks have attracted considerable attention in the last few years due to their valuable civil and military applications. One aspect of such networks that has been studied insufficiently is the energy efficiency. Energy efficiency is crucial to prolong the network lifetime and thus make the network more survivable.Nodes in wireless ad hoc networks are most likely to be driven by battery and hence operate on an extremely frugal energy budget. Conventional ad hoc routing protocols are focused on handling the mobility instead of energy efficiency. Energy efficient routing strategies proposed in literature either do not take advantage of sleep modes to conserve energy more efficiently, or incur much overhead in terms of control message and computing complexity to schedule sleep modes and thus are not scalable.In this dissertation, a novel strategy is proposed to manage the sleep of the nodes in the network so that energy can be conserved and network connectivity can be kept. The novelty of the strategy is its extreme simplicity. The idea is derived from the results of the percolation theory, typically called gossiping. Gossiping is a convenient and effective approach and has been successfully applied to several areas of the networking. In the proposed work, we will developa sleep management protocol from gossiping for both static and mobile wireless ad hoc networks. Then the protocol will be extended to the asynchronous network, where nodes manage their own states independently. Analysis and simulations will be conducted to show thecorrectness, effectiveness and efficiency of the proposed work. The comparison between analytical and simulation results will justify them for each other. We will investigate the most important performance aspects concerning the proposed strategy, including the effect ofparameter tuning and the impacts of routing protocols. Furthermore, multiple extensions will be developed to improve the performance and make the proposed strategy apply to different network scenarios
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