Atanu Roy Chowdhury

Power Efficient and Low Latency MAC for Wireless Sensor Networks

Existing protocols for medium access in wireless sensor networks opt for staggered wakeup scheduling among clusters of nodes. However intra-cluster contention and interference has remained an unaddressed issue. In this work we propose PELLMAC: power efficient and low latency MAC for wireless sensor networks, a schema that addresses node scheduling for channel access. By limiting contention between adjacent branches of the data gathering tree, we are able to reduce the latency of the network, as well as optimize energy utilization. Simulation results, in accordance with our claims, show that PELLMAC enhances performance in energy savings, latency and delivery ratio

Securing Wireless Sensor Networks Against Spurious Injections

Wireless sensor networks (WSNs) are best suited for perceiving a phenomenon, which in turn forms the basis for controlling an actuator in a corrective plane. However, before the corrective action can be invoked, it is necessary to validate that the data was not injected with a malicious intent. To this end we propose CADA (cellular automata based data authentication mechanism), a lightweight protocol to authenticate data from valid nodes. Unlike its predecessors, it is designed to assume scarcity of multiple resources viz power, processing, storage, bandwidth and radio range.CADA takes advantage of the concurrent operations in cellular automata components and is therefore not only fast but also easily realizable in hardware.

BOWL: Design and implementation of a (connectionless) broadcasting system over wireless LAN

A truly pervasive computing environment can only be created if ubiquitous computation power can collaborate seamlessly to create superior user experience. With the adoption of mobile computing platforms on the rise, we have explored how the IEEE 802.11 wireless access standards can be used to enable a device to be more aware of the capabilities of the infrastructure in its surroundings. Specifically, we have been able to effectively transfer information to these WiFi enabled devices without explicit connections being established and therefore our solution is proven to be much more scalable. We have also showcased a pilot application using the broadcast over wireless LAN (BOWL) technology.

LLM:Low Latency MAC Protocol for Wireless Sensor Networks

Wireless sensor networks aim at a special kind of ad hoc networks, exposing an energy-constrained distributed computing environment. Proposed protocols have tried to incorporate power management schemas of the likes of reduced duty cycles and active synchronization. However this has led to a significant loss in the latency of data delivery. In this work we have introduced low latency medium access control (LLM), as a mechanism to deliver data with low latency without compromising the energy efficiency of the network. To this end we exploit the data aggregating properties of a sensor network and introduce a pre-notification packet to keep potential forwarding nodes aware of a forthcoming data packet. Our simulations show that LLM does perform as per expectations

mConnect: A context aware mobile transaction middleware

Enterprises are aggressively eyeing ubiquitous mobile solutions to increase the efficiency of their taskforce, but this exercise is hindered by several functional and technical challenges. For instance mobile devices are widely different in terms of their underlying platform capabilities, available screen real estate, input mechanisms and so on. In this work we introduce mConnect, a Context aware real time Mobile Transaction Middleware which manages this device diversity in an efficient manner. mConnect abstracts the complexities of the mobile world from the existing infrastructure and seamlessly helps in extending/ creating internet based transaction solutions for mobile users with minimal or no modification to the back-end. This in turn accelerates the adoption of the mobile device as a default channel to access the Web.

Improving MAC Layer Fairness in Multi-Hop 802.11 Networks

Wireless adhoc networks consist of nodes interconnected by wireless multi-hop communication paths. Such networks exhibit simulated mobility, where the topological changes are caused by nodes coming up or going down. These networks also exhibit complex overlapping of flow paths. This in turn leads to severe contention in between flows as well as between the sub-flows of the same flow. In this paper, we analyze the unfairness of IEEE 802.11, in case it is extended for multi-hop networks. Thereafter we demonstrate how a simple, distributed algorithm can be put in place to approximate an ideal scheduler like round-robin and provide fair access to all the flows. Our simulation results clearly show that such an approach outscores the existing standard on fairness grounds. Additionally we also gain in terms of throughput by reducing the number of collisions.

Received signal based minimization of broadcast storm in multi-hop MANET

The absence of guaranteed static reference nodes in a dynamic MANET environment makes it almost impossible to control the propagation of a broadcast packet in a controlled fashion. Therefore, to offset the well documented inefficiencies of a simple flooding mechanism, we propose optimal reliability broadcast mechanism (ORBM). ORBM is a received signal strength based scheme to control temporal congestion (arising out of broadcast storms) and reducing rebroadcast redundancy. Our main focus has been the prioritization of retransmissions from nodes which cover maximum virgin territory. Moreover, ORBM is topology adaptive, in the sense that there is higher rebroadcast suppression in a dense neighborhood than in a sparse one. Our simulations show that ORBM is highly scalable and practically immune to neighbor density as well as mobility. The strength of ORBM lies in the cost of a flood growing linearly with the network diameter

Survey of broadcasting techniques for dense wireless computing devices

Broadcasting is a fundamental operation in any network, more so in a wireless environment where the media is inherently broadcast in nature. The absence of guaranteed static reference nodes in a dense and dynamic wireless computing environment makes it almost impossible to control the propagation of a broadcast packet. In this work we survey the various techniques adopted to minimize the temporal traffic storms associated with broadcasting a packet. We also cover proposals aimed at increasing the reliability and reachability of the broadcast operation

CARA: Cellular Automata Based Remote-User Authentication Scheme

User authentication is most essential to prevent the unauthorized adversaries from obtaining the system resources. This paper proposes a cellular automata based remote-user authentication (CARA) scheme to reduce the complexity of encryption and hash-based cryptosystems. CARA uses cache-based nonce to avoid synchronization problems and thwart replay attacks. This scheme is robust against other attacks as well. The inherent parallelism of cellular automata provides for its fast implementation