Kumar Padmanabh

iSense: a wireless sensor network based conference room management system

In this paper, we have studied the IT system (e.g. MS-outlook) that is used to book meeting rooms in a corporate environment. In the existing IT system, the status of meeting rooms is manually entered, and as a result, it is not reflected in real time in the IT system. This results in severe underutilization of resources (conference rooms) across the corporation, and wastage of electricity with the lights and air-conditioning system being operational even when the rooms are unoccupied. We have created a test bed of motes and analyzed the occupancy and electricity consumption data to estimate the under-utilization of conference rooms, and the wastage of electricity in the process. In order to eliminate these problems, we have designed a wireless sensor network based solution which results in two main benefits: (i) the utilization of the conference room is increased from 67% to 90% and (ii) electricity saving is equivalent to 16000 full grown banyan trees in a year.

Incorporating fairness within Demand response programs in smart grid

Basic Demand response (DR) programs aim to modulate the demand of electricity in accordance with its supply. The existing DR programs have only been of limited success, though the participation has steadily increased in the recent past. This paper establishes the lack of fairness principles within the DR programs, as perceived by the customers to be one of the key deterrents. Fair DR (FDR) scheme criteria are defined and compared with existing pricing schemes. In this context, a simplified pricing model that takes into consideration fairness criteria for residential category is also proposed in this paper. The proposed pricing model is simulated in Gridlab-D and the results are compared with that of the flat and the price based pricing schemes. Initial results establish that our pricing scheme is fair, it flattens the demand curve over a day and provides a win-win situation for both - the customer and the utility company.

A Scalable WSN Based Data Center Monitoring Solution with Probabilistic Event Prediction

The two most important objectives of the data center operators are to reduce operating cost and minimize carbon emission. Consolidation of data centers is not always possible and big enterprise end up having data centers in multiple locations across different cities and countries. In such a diverse deployment manual monitoring is not a cost effective solution. ASHRAE [1] suggested considering the energy efficiency as key factor in data center design. Our initial experiments reveal that a reduction in one degree Celsius of data center room temperature results in 4% excess consumption of electricity. We developed a WSN based data center monitoring (DCM) solution which includes the hardware system and an enterprise application. We deployed the hardware system in hundreds of location at 7 different cities and monitored them from a central enterprise application dashboard. In this paper, we describe the system architecture and analyzed data that was captured for nine months. This is one of the largest real life WSN deployment and based on the result we argue that the manual monitoring cost of data centers is reduced by 80%. This deployment also helped in avoiding a significant amount of carbon emission. DCM also provides a mechanism to predict events in real time.

Prioritized Buffer Management Policy for Wireless Sensor Nodes

In wireless sensor node battery power and memory is available in limited amount. The computing devices available in the sensor nodes are not capable enough to execute complex algorithm. Moreover, several retransmissions of data packets are done to compensate lost packet due to buffer overflow. The algorithm of buffer management policies of conventional data network cannot be applied in sensor network, because they are too complex to be implemented in low computation capable sensor nodes. There are many aspect of this paper, firstly we proposed to classify the packets into different categories and then we proposed the prioritized buffer management policy for different category uniquely. Currently, the CMU priority queue system available with the default DSR algorithm is being used in wireless sensor network. Our analysis and simulation studies show that our policies can be used to save all critically important packets. The other results indicate that our proposed algorithm outperform the CMU priority queue management available with DSR protocol.

An Adaptive Data Aggregation Algorithm in Wireless Sensor Network with Bursty Source

The Wireless Sensor network is distributed event based systems that differ from conventional communica-tion network. Sensor network has severe energy constraints, redundant low data rate, and many-to-one flows. Aggregation is a technique to avoid redundant information to save energy and other resources. There are two types of aggregations. In one of the aggregation many sensor data are embedded into single packet, thus avoiding the unnecessary packet headers, this is called lossless aggregation. In the second case the sensor data goes under statistical process (average, maximum, minimum) and results are communicated to the base station, this is called lossy aggregation, because we cannot recover the original sensor data from the received aggregated packet. The number of sensor data to be aggregated in a single packet is known as degree of ag-gregation. The main contribution of this paper is to propose an algorithm which is adaptive to choose one of the aggregations based on scenarios and degree of aggregation based on traffic. We are also suggesting a suitable buffer management to offer best Quality of Service. Our initial experiment with NS-2 implementa-tion shows significant energy savings by reducing the number of packets optimally at any given moment of time.

On social behavior of wireless sensor node

In this paper, we study a wireless sensor network (WSN) as a social network in which the embedded sensors are the main entities as opposed to human beings in a traditional social network. In wireless sensor networks, the nodes resemble individuals in a way that they communicate with their peers, sometimes selectively hiding some information, sometimes selectively exposing some other information, generating or forwarding information, sharing resources, joining and/or leaving the network. We argue in this paper that nodes of the sensor network have their own social life, and based on that assumption, we leverage ideas from social networks to show how the nodes can communicate in a “social networking” style to achieve significant efficiency. Specifically, we study the performance of WSN when some common rules of social network are applied in WSN and show significant reduction of overhead traffic leading to longer battery life of embedded nodes and better utilization of the network. Results from theoretical analysis have been verified through experimental study to justify the benefits of treating WSN as a social network.

Transmission range and density gradient management to avoid bottleneck around base station in wireless sensor network

Base station is a special node in a sensor network. It connects an individual sensor node to the outside world. Mostly base stations have sufficient battery power. However, the nodes which are in the proximity of base station have limited battery power. The information generated by other nodes gets shipped to the base station via the nodes which are adjacent to the same. Thus in addition to the information generated by them, the nodes around the base station also have to forward the data of other nodes to the base station. In this way these nodes will have to bear more communication responsibilities than peripheral nodes. The batteries of these nodes get exhausted rapidly and thus they create a bottleneck for prolonged communication. In this paper, we propose to optimise the topology by optimising the transmission power and introducing redundancy in the system in different topological scenarios to avoid this bottleneck phenomenon. The analytical and experimental results demonstrate that using our proposed algorithm all nodes will exhaust its battery at almost the same moment of time. There will no more be a bottleneck in prolonged communication.

An Efficient Method for Synchronizing Clocks of Networked ECUs in Automotive Systems

Advanced active-safety-critical automotive applications require close coordination of different activities including sensing, processing and actuations, typically performed by different Electronic Control Units (ECU) connected over a communication network. It is imperative that ECUs executing these tasks have a common reference of time. In a distributed system, a periodic resynchronization is a common approach to ensure this. In this paper, we have proposed a new protocol for clock synchronization keeping resource-constraints automotive systems. Our specific contributions include: (a) as compared to standard treatment of drift as a linear function of time, we use a realistic non-linear model of drift, and (b) in order to minimize communication overhead, we propose an algorithm to anticipate the time at which a specific ECU would go out of sync and participate only such identified ECUs for resynchronization instead of all ECUs, as traditionally done. Analytical results show that the proposed protocol incurs minimal communication as well computational load on the ECUs.

senSebuddy: a buddy to your wireless sensor network

The sensor data are used by end users using various IT applications. The typical application for monitoring, querying and controlling the deployed Wireless Sensor Network is complex in nature from application development point of view, owing to various resource limitations. Post-deployment nuances like firmware update, addition of new nodes or replacement of others are not so easy task, either. In recent past, efforts have been made to minimize the complexity of end user through desktop and web-based application. However, so far, instant messaging has not been tried for communication between an end user and physical mote, where an individual sensor node (or group of them) appearing as a buddy in the instant messaging contact list and one can talk to it. In this paper we are describing a system that we developed recently with the name senSebuddy, based on instant messaging technique to monitor, query and control the deployed WSN applications. We also describe the functionality of the prototype implementation of the system with Smack XMPP API and Openfire XMPP server [7]. We have carried out series of experiments to prove that one can chat with sensor mote like a normal human being, and mote can be programmed using gtalk without experiencing any delay.

A tool to determine strategic location and ranges of nodes for optimum deployment of wireless sensor network

The deployment of wireless sensors is very challenging, yet it is one of the most unexplored areas of this domain. In most of the WSN applications, the sensing location is fixed. In this paper, we are describing a deployment tool we have developed for strategic localization and network optimization. Even before going into field deployment, this tool can be used to calculate precisely the location of the nodes and transmission range while considering line of sight and obstacle into account. The JPEG image of the terrain or floor plan and line of sight or obstacle are the input parameters. The algorithm used in this tool addresses two aspects of the problems: how to minimize the range of the sensor nodes while still forming a well connected network and how to find the location of the forwarding nodes such that the energy required in communication is minimum. Based on these algorithms we have developed a tool to calculate the network parameters such as minimum numbers of forwarding nodes, minimum range for each node required to form a well connected mesh network and minimize the power consumption. Our initial experiments with google maps give very encouraging results.