Tarun Banka

Static allocation of resources to communicating subtasks in a heterogeneous ad hoc grid environment

An ad hoc grid is a heterogeneous computing and communication system that allows a group of mobile devices to accomplish a mission, often in a hostile environment. Energy management is a major concern in ad hoc grids. The problem studied here focuses on statically assigning resources in an ad hoc grid to an application composed of communicating subtasks. The goal of the allocation is to minimize the average percentage of energy consumed by the application to execute across the machines in the ad hoc grid, while meeting an application execution time constraint. This pre-computed allocation is then used when the application is deployed in a mission. Six different heuristic approaches of varying time complexities have been designed and compared via simulations to solve this ad hoc grid allocation problem. Also, a lower bound based on the performance metric has been designed to compare the performance of the heuristics developed.

Zonal rumor routing for wireless sensor networks

Routing algorithms for wireless sensor networks are constrained by power, memory and computational resources. Rumor routing algorithm for sensor-networks spreads the information of an event to other nodes in the network, thus enabling queries to discover paths to the events. Zonal rumor routing (ZRR) is an extension to the rumor routing algorithm. ZRR algorithm enables the rumors to spread to a larger part of the network with high energy efficiency by partitioning the network into zones. New algorithm improves the percentage query delivery and requires fewer transmissions, thus reducing the total energy consumption in a sensor network. Rumor routing can be considered as a special case of ZRR when only one node belongs to one zone. The performance of ZRR, the effect of zone size, and the scalability of the algorithm are evaluated using simulations.

Static mapping of subtasks in a heterogeneous ad hoc grid environment

Summary form only given. An ad hoc grid is a heterogeneous computing and communication system without a fixed infrastructure; all of its components are mobile. Energy management is a major concern in an ad hoc grid. One important aspect of energy management is to minimize the energy consumption during a mission. In an ad hoc grid, communication and computations are deeply intertwined, and any energy optimization must consider both types of activities together rather than separately. The mapping (defined as matching and scheduling) of tasks onto machines with varied computational capabilities has been shown, in general, to be an NP-complete problem. Therefore, heuristic techniques are required to efficiently map tasks to machines in an ad hoc grid so as to minimize the energy consumed due to communication and computation. This research evaluates and compares energy management issues for resource allocation in ad hoc grids using six static heuristics.

Performance Degradation of IEEE 802.15.4 Slotted CSMA/CA due to Hidden Nodes

As sensor nodes are subject to strict power limitations and often deployed in harsh environments, there is significant potential for a node to be hidden from another node. The impact of hidden nodes on performance of the IEEE 802.15.4 low-rate wireless personal area network protocol is evaluated. At lower Tx power, as a result of hidden nodes, there are more collisions in the network increasing the cost of packet delivery. The simulation results indicate that there exists an optimum transmission power that minimizes the impact of hidden nodes, and it depends on factors such as network load, desired throughput and beacon order. Results indicate that additional throughput gain and lower cost per packet delivered can be achieved by increasing the beacon order at higher Tx power.

On reorder density and its application to characterization of packet reordering

A formal approach for characterizing, evaluating and modeling packet reordering is presented. Reordering is, a phenomenon that is likely to become increasingly common on the Internet, and it can have an adverse impact on end-to-end performance and network resource utilization. Reorder density (RD) is a comprehensive metric for reordering. Several properties of RD are presented that provide insight into the nature of reordering present in a sequence. Based on measurements of packet reordering, certain basic patterns of reordering that are prevalent on the Internet are identified. By focusing on these basic patterns, a model is developed for reordering in networks involving two parallel paths, using a simple load-balancing scenario as an example. The model is verified using an emulation testbed

Mapping of subtasks with multiple versions in a heterogeneous ad hoc grid environment

An ad hoc grid is a heterogeneous computing system composed of mobile devices. The problem studied here is to statically assign resources to the subtasks of an application, which has an execution time constraint, when the resources are oversubscribed. Each subtask has a preferred version, and a secondary version that uses fewer resources. The goal is to assign resources so that the application meets its execution time constraint while minimizing the number of secondary versions used. Five resource allocation heuristics to derive near-optimal solutions to this problem are presented and evaluated.

An Architecture and a Programming Interface for Application-Aware Data Dissemination Using Overlay Networks

Many real-time distributed collaborative applications are emerging that require exchange of critical sensor data among geographically distant end users under resource-constrained network conditions. The QoS requirements, e.g., required bandwidth, latency, acceptable data quality, and reliability are interdependent, and critical to the operation of these applications. This paper presents an AWON (application-aware overlay networks) architecture for deploying application-aware services in an overlay network to best meet the application requirements over the available overlay networking infrastructure. An application programming interface (API) is presented to facilitate development of applications within the AWON architectural framework. The API supports the configuration of overlay nodes for in-network, application-aware processing. Application-defined plug-in modules are used to deploy application-specific functionality at each overlay node. The API also enables communication between application and the overlay routing protocol for the desired QoS support. The effectiveness of the AWON architecture and the API is demonstrated for a real-time weather radar data dissemination application using planetlab. Experimental results show that AWON-based application-aware services significantly improve the quality of the content delivered to the end users in bandwidth-constrained conditions.

Impact of Network Dynamics on Tardiness of Data in Sensor Networks

Impact of random delays and losses in sensor networks manifests in the form of tardiness of data used for processing at the sink nodes. The age of data used by the end application can impact the accuracy of the end results, and may produce detrimental consequences for many real-time sensing applications. This paper uses a tardiness measure for quantitatively capturing the lateness of the data due to network dynamics, and presents an analytical model relating the network delay, network packet loss rate, packet reordering, and sampling rate to the tardiness. We extend this model to provide aggregate weighted tardiness of data at fusion nodes. The tardiness model is validated using simulation results. We also investigate the tradeoffs between energy consumption and tardiness when desired tardiness is achieved by adjusting sampling rate and transmission power of the sensors nodes. Other potential applications of proposed tardiness measure includes determination of the active/sleep period of MAC layer to meet application goals, and comparison of routing protocols based on their impact on tardiness, and hence the application in real-time sensor networks.

Application Aware Overlay One-to-Many Data Dissemination Protocol for High-Bandwidth Sensor Actuator Networks

An application-aware deterministic overlay one-to-many (DOOM) protocol is proposed for meeting heterogeneous QoS requirements of multiple end users of high-bandwidth sensor actuator network (HB-SAN) applications. Although DOOM is initially targeted for use in collaborative adaptive systems of weather radars, it has been designed for use in wider class of sensing systems. DOOM protocol performs rate-based application aware congestion control by selecting end user specific subset of the sensor data for transmission thus adapting to available network infrastructure under dynamic network conditions. Performance of DOOM is evaluated for radar networking using a combination of Planetlab as well as an emulation based test-bed. It is shown that DOOM protocol is able to meet individual end user QoS requirements as well as aggregate QoS requirements of different end users. Moreover, multiple DOOM streams are friendly to each other as well as to TCP cross- traffic sharing the bottleneck link

Content-based Packet Marking for Application-Aware Processing in Overlay Networks

In many emerging sensing applications, random network losses may lead to drop of critical information, rendering partially received data useless for the end users. A packet-marking scheme based on the application content is proposed that enables application-aware processing of the data within the overlay network. A token-bucket based rate control algorithm in conjunction with the proposed packet-marking scheme enables on-the-fly selection of data for forwarding/drop to a particular end user at the desired transmission rate. We demonstrate the effectiveness of the packet-marking and token-bucket based rate control scheme in simultaneously meeting heterogeneous QoS requirements of the multiple end users for content quality and bandwidth for a weather monitoring sensing application