Partha Sarathi Mandal

Concurrent checkpoint initiation and recovery algorithms on asynchronous ring networks

Checkpointing with rollback recovery is a well-known method for achieving fault-tolerance in distributed systems. In this work, we introduce algorithms for checkpointing and rollback recovery on asynchronous unidirectional and bi-directional ring networks. The proposed checkpointing algorithms can handle multiple concurrent initiations by different processes. While taking checkpoints, processes do not have to take into consideration any application message dependency. The synchronization is achieved by passing control messages among the processes. Application messages are acknowledged. Each process maintains a list of unacknowledged messages. Here we use a logical checkpoint, which is a standard checkpoint (i.e., snapshot of the process) plus a list of messages that have been sent by this process but are unacknowledged at the time of taking the checkpoint. The worst case message complexity of the proposed checkpointing algorithm is O(kn) when k initiators initiate concurrently. The time complexity is O(n). For the recovery algorithm, time and message complexities are both O(n).

Deterministic Secure Positioning in Wireless Sensor Networks

Position verification problem is an important building block for a large subset of wireless sensor networks (WSN) applications. As a result, the performance of the WSN degrades significantly when misbehaving nodes report false location information in order to fake their actual position. In this paper we propose the first deterministic distributed protocol for accurate identification of faking sensors in a WSN. Our scheme does notrely on a subset of trustednodes that cooperate and are not allowed to misbehave. Thus, any subset of nodes is allowed to try faking its position. As in previous approaches, our protocol is based on distance evaluation techniques developed for WSN. On the positive side, we show that when the received signal strength (RSS) technique is used, our protocol handles at most

Line sweep coverage in wireless sensor networks

\lfloor \frac{n}{2} \rfloor-2

A comparative study of deterministic and stochastic dynamics for a non-autonomous allelopathic phytoplankton model

faking sensors. When the time of flight (ToF) technique is used, our protocol manages at most

Performance analysis of different checkpointing and recovery schemes using stochastic model

\lfloor \frac{n}{2} \rfloor - 3

Checkpointing Using Mobile Agents in Distributed Systems

misbehaving sensors. On the negative side, we prove that no deterministic protocol can identify faking sensors if their number is

Approximation algorithm for sweep coverage on graph

\lceil \frac{n}{2}\rceil -1

Reconstruction of aggregation tree in spite of faulty nodes in wireless sensor networks

. Thus, our scheme is almost optimal with respect to the number of faking sensors. We discuss application of our technique in the trusted sensor model. More specifically, our results can be used to minimize the number of trusted sensors that are needed to defeat faking ones.

MOBILE AGENT BASED CHECKPOINTING WITH CONCURRENT INITIATIONS

Traditional coverage in wireless sensor networks requires continuous monitoring of target objects or regions. Unlike traditional coverage, periodic monitoring by a set of mobile sensor nodes is sufficient in sweep coverage. The sweep coverage problem for covering a set of points is NP-hard and it cannot be approximated within a factor of 2 [15]. The sweep coverage problem for a given bounded region is also NP-hard [11]. In this paper, we study sweep coverage for covering a set of line segments on a plane. We prove that the problem is NP-hard and cannot be approximated within a factor 2. Our proposed algorithm achieves the best possible approximation factor 2. As an application of line sweep coverage problem we formulate a data gathering problem, where minimum number of data mules periodically collect data from a set of mobile sensor nodes. The mobile sensor nodes arbitrarily move along their paths, which are line segments. We prove that this problem is NP-hard and propose a 3 approximation algorithm to solve it.

Path planning algorithms for mobile anchors towards range-free localization

Abstract In this paper, we investigate a non-autonomous competitive phytoplankton model with periodic coefficients in deterministic and stochastic environment, respectively. We prove the existence of at least one positive periodic solution together with it’s global asymptotic stability. The existence of periodic solution has been obtained by using the continuation theorem of coincidence degree theory proposed by Gaines and Mawhin. We formulate the corresponding stochastic model by perturbing the growth rate parameters by white noise terms. We prove that all the higher order moments of the solution to the stochastic system is uniformly bounded which ensure that the solution of the stochastic system is stochastically bounded. We provide easily verifiable sufficient conditions for non-persistence in mean, extinction and stochastic permanence of the stochastic system. Sufficient condition for permanence shows that if the noise intensity is very low then the solution of the stochastic system persists in the periodic coexistence domain of the deterministic system. We perform exhaustive numerical simulations to validate our analytical findings.