Improving partial cover of Random Walks in large-scale Wireless Sensor Networks

Proceedings of the Second International Workshop on Mobile Opportunistic Networking

2010

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Random walk-based approaches are suitable for information dissemination in mobile and opportunistic environments that are inherently dynamic and typically large-scale. Multiple random walkers have been proposed in the recent past as a suitable mechanism to significantly reduce termination time when covering a network topology. In this paper, the multiple random walkers mechanism is studied and analyzed under a different and novel perspective that allows for further understanding of network coverage when employing multiple random walkers in a network. Given that under this mechanism the number of movements is significantly increased (proportional to the number of random walkers) -and sometimes not as effective as expected due to frequent revisits that do not improve coverage as shown in this paper -a replication mechanism is introduced that is capable of reducing the number of movements by reducing initial revisits. Simulation results considering geometric random graph topologies -which are suitable for modeling mobile environments -are also presented supporting the analytical findings and shedding more light on various aspects of both the aforementioned mechanisms.

Section: Past Related Workmentioning

confidence: 99%

“…These approaches among others include random walkers with jumps [14], random walkers replication [7], multiple random walkers [3], hybrid approaches [5]. Further information about various dissemination information approaches is given in Section 2.…”

Section: Introductionmentioning

confidence: 99%

A study of information dissemination under multiple random walkers and replication mechanisms

Οικονόμου

Kogias

Proceedings of the Second International Workshop on Mobile Opportunistic Networking

2010

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“…This directional movement mechanism or jumping, initially proposed in [19], can be realized by switching occasionally away from the random walk without backtracking operation and engaging an operation implementing a directional movement. That is, such a RW-agent (to be referred to as the Jumping Random Walk agent (J-RW-agent)) operates under two states: State 0 under which it implements the typical random walk without backtracking mechanism, and State 1 during which the directional move is implemented; the time spent in State 1 (freezing state) will be referred to as the freezing (the direction) period.…”

Section: Motivationmentioning

confidence: 99%

“…In this paper the Jumping Random Walk (J-RW) mechanism, originally proposed in [19], is shown both analytically and experimentally to be an efficient random walk based information dissemination/ retrieval mechanism for large-scale RGGs. The contributions in this paper, in addition to presenting the J-RW mechanism, include analytical results about the coverage of the RW-agent and J-RW-agent and a new set of simulation experiments to validate the analytical findings on coverage.…”

Section: Introductionmentioning

confidence: 99%

Random walk with jumps in large-scale random geometric graphs

Tzevelekas

Οικονόμου

Computer Communications

2010

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a b s t r a c tThe information dissemination problem in large-scale networking environments like wireless sensor networks and ad hoc networks is studied here considering random geometric graphs and random walk based approaches. A new type of random walk based agent is proposed in this paper and an analytical expression with respect to coverage (i.e., the proportion of the network nodes visited by the random walk agent) as a function of the number of the agent movements is derived. It is observed that the cover time of many of already existing random walk based variants is large in random geometric graphs of low degree (as it is commonly the case is wireless environments). As this inefficiency is attributed (as discussed in the paper) to the inability of existing random walk based solutions to move away from already likely covered areas, a mechanism for directional movement (i.e., jumping) of the random walk based agent is proposed and studied, that allows the agent to jump to different network areas, most likely not covered yet. The proposed mechanism (Jumping Random Walk) is studied analytically and via simulations and the parameters (of the network topology and the mechanism) under which the proposed scheme outperforms existing random walk based variations are determined.

“…1 illustrates a realization of the movement of the mobile sink under the RW-based sink mobility scheme. As the sink movement is probabilistic in nature, it is likely that already visited nodes are revisited in the future ( [17]). These revisits impact negatively on both the energy consumption of the sensor nodes and the physical distance spanned (or delay suffered) by the mobile sink.…”

Section: A Random Walk-based 1-hop Data Collection Schemementioning

confidence: 99%

Sink mobility schemes for data extraction in large scale WSNs under single or zero hop data forwarding

Tzevelekas

2010 European Wireless Conference (EW)

2010

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Abstract-A mobile sink is widely considered to facilitate the data collection from energy constrained sensor fields, by having the sink come close to the sensors and conserving precious sensor node energy. The effectiveness of such a data collection approach can be measured in terms of the sensor energy conserved and the time required to collect the sensor data from the field (or, equivalently, the length of the trajectory implemented by the mobile sink).In this paper we explore two important dimensions in the design of mobile sink-based data collection schemes. One dimension refers to how close to the sensor nodes the sink moves to, to collect the data, which impacts on the transmission energy expenditure by the sensor node. The other dimension refers to the way the sink moves through the sensor field, to collect the data, which impacts on the delay in collecting the data. To capture the first dimension, the 0-hop and 1-hop data collection schemes are considered and studied; at the same time, two "extreme" approaches to the sink mobility process are considered: a (topology unaware) random walk-based sink mobility scheme and a (topology aware, optimal) deterministic sink mobility scheme. Through the analytic and simulative study presented in this paper, an understanding of the level of the trade-offs involved between the energy spent by the sensor nodes and the delay in completing the data collection process is obtained.