Bijendra N. Jain

Experimental assessment of end-to-end behavior on Internet

A simple experiment designed to capture the end-to-end behavior of the Internet is described. The measurements indicate that the IP level service provided in the network yields high losses, duplicates, and reorderings of packets. In addition, the round-trip transit delay varies significantly. These measurements indicate that the network may have several problems which still need to be analyzed in order to improve the efficiency of protocols and control mechanisms that it uses.<<ETX>>

Experimental analysis of RSSI-based location estimation in wireless sensor networks

With a widespread increase in the number of mobile wireless systems and applications, the need for location aware services has risen at a very high pace in the last few years. Much research has been done for the development of new models for location aware systems, but most of it has primarily used the support of 802.11 wireless networks. Less work has been done towards an exhaustive error analysis of the underlying theories and models, especially in an indoor environment using a wireless sensor network. We present a thorough analysis of the Radio Signal Strength (RSS) model for distance estimation in wireless sensor networks through an empirical quantification of error metrics. Further on the basis of this experimental analysis, we implement a k - nearest signal space neighbor match algorithm for location estimation, and evaluate some crucial control parameters using which this technique can be adapted to different cases and scenarios, to achieve finer and more precise location estimates.

Random and Periodic Sleep Schedules for Target Detection in Sensor Networks

We study random and periodic sleep schedules from the point of view of delay in detecting the target. We consider sleep schedules in which a sensor in “inactive” mode wakes up either randomly or periodically to detect presence of the target within its vicinity resulting into two sleep schedules: (a) random wake-up schedule, and (b) periodic wake-up schedule respectively. Specifically, we analyse and obtain for the random wake-up schedule the expected delay in detection, and the delay, such that with probability P, the delay is less than the computed value. For the periodic wake-up schedule we show that there exists an upper bound on the delay. Further we compute the average value of delay. We have shown that the theoretically computed averages and the upper bounds on the delay match with the simulation results for the random wake-up and periodic wake-up schedules.

An analytical framework for path reliabilities in mobile ad hoc networks

An ad hoc network is a collection of mobile nodes connected through multi-hop wireless links without the required intervention of any centralized access point or existing infrastructure. In this work, we have developed an analytical framework for computing the reliabilities of multi-hop paths. We have also investigated the effect of multi-path characteristics on path reliabilities. Among the main parameters considered here are, average link clustering, number of multiple paths, path complexity factor, and hop difference factor. Our approach is unified and general in the sense that it is able to incorporate single as well a multiple paths between a given source and destination pair.

Path Diminution is Unavoidable in Node-Disjoint Multipath Routing with Single Route Discovery

In an ad hoc network, identification of all node-disjoint paths between a given pair of nodes is a challenging task. The phenomena that a protocol is not able to identify all node-disjoint paths that exist between a given pair of nodes is called path diminution. In this paper, we discuss that path diminution is unavoidable when a protocol discovers multiple node-disjoint paths in a single route discovery. We discuss schemes to mitigate path diminution. However, no such scheme is guaranteed to discover all node-disjoint paths that exist between a given pair of nodes. We have proved that one cannot devise an efficient algorithm that is guaranteed to compute all node-disjoint paths between a given pair of nodes in a single route discovery

Path diminution in disjoint multipath routing for mobile ad hoc networks

An ad hoc network is a collection of mobile nodes connected through multi-hop wireless links without the required intervention of any centralized access point or existing infrastructure. Design of disjoint multipath routing protocols in an ad hoc environment is a challenging task. We have considered disjoint multipath routing schemes with path diminution in an ad hoc environment. Also, we have discussed the trade-off between the number of multiple paths searched and route establishment overheads.

Path diminution in node-disjoint multipath routing for mobile ad hoc networks is unavoidable with single route discovery

In an ad hoc network, identification of all node-disjoint paths between a given pair of nodes is a challenging task. The phenomena that a protocol is not able to identify all node-disjoint paths that exist between a given pair of nodes is called path diminution. In this paper, we discuss that path diminution is unavoidable when a protocol discovers multiple node-disjoint paths in a single route discovery. We discuss schemes to mitigate path diminution. However, no such scheme is guaranteed to discover all node-disjoint paths that exist between a given pair of nodes. We have proved that one cannot devise an efficient algorithm that is guaranteed to compute all node-disjoint paths between a given pair of nodes in a single route discovery.

Localization accuracy and threshold network density for tracking sensor networks

Localization of target is one of the core issues in target tracking. This paper analyzes mathematical techniques of localization from the view point of error in position estimation. It is observed that error in position estimation reduces as the number of sensors making measurement to the target increase. Moreover, it is dependent on the positions of sensors making measurements to target node and on the error in measurement. The error in position estimation is least when the sensors making measurement to the node are well distributed in all the directions around the target node. It has been analyzed that after a particular number of well distributed nodes making measurements to the target node there is no significant reduction in position estimation error. Due to the random nature of deployment of sensors, saturation in accuracy is reached after around eight neighbors making measurement to the target. The paper makes a significant contribution by analyzing and establishing an optimum threshold bound for network density such that the accuracy in position estimation is maximum.

Routing reliability analysis of segmented backup paths in mobile ad hoc networks

Several real-time applications (e.g., video conferencing, remote control systems) demand guarantees on message delivery latency. Supporting such QoS constrained connections requires the existence of a routing mechanism which computes paths that satisfy QoS constraints. In a mobile ad hoc network, wireless links tend to fail frequently as nodes move in and out of transmission range of one another. Providing fault tolerance with QoS guarantees in such networks is challenging. An algorithm called segmented backup source routing (SBSR) provides fault tolerance with end-to-end delay as the QoS parameter. The algorithm constructs a set of delay-constrained segmented backup paths. Each such segmented backup path protects a segment of the primary path rather than the entire path. This approach has two advantages. First, one is able to identify backup paths for any selected primary path, as long as there exists a pair of node disjoint paths from source to destination (in other words, if there are two node disjoint paths, it is not required to use either of them as the primary path). This has the advantage that the primary path may be selected based on QoS considerations rather than a consideration of fault tolerance. The second significant advantage is that the connection reliability of the segmented backup path set is higher than the two disjoint paths. We design a framework to analyse the connection reliability of such a segmented backup path set.

An Analytical Framework for Route Failure Time of Multiple Node-Disjoint Paths in Mobile Ad hoc Networks

In a mobile ad hoc network, routes may often fail due to movements of nodes. In this paper, we analyze route failure time of multiple node-disjoint paths between a given pair of nodes. We discuss an exact expression for the expected value of route failure time when lifetimes of individual paths are independent and identically distributed random variables. In case lifetimes are not independent, we discuss an upper bound on route failure time. In order to validate the model, we simulate exponentially distributed random variables. Values of route failure time obtained from simulations are close to those obtained analytically