http://www.eecs.ucf.edu/~dcm/Teaching/COT4810-Spring2011/Literature/SensorNetworksSurvey.pdf

Wireless sensor networks: a survey

Wireless distributed microsensor systems will enable the reliable monitoring of a variety of environments for both civil and military applications. In this paper, we look at communication protocols, which can have significant impact on the overall energy dissipation of these networks. Based on our findings that the conventional protocols of direct transmission, minimum-transmission-energy, multi-hop routing, and static clustering may not be optimal for sensor networks, we propose LEACH (Low-Energy Adaptive Clustering Hierarchy), a clustering-based protocol that utilizes randomized rotation of local cluster based station (cluster-heads) to evenly distribute the energy load among the sensors in the network. LEACH uses localized coordination to enable scalability and robustness for dynamic networks, and incorporates data fusion into the routing protocol to reduce the amount of information that must be transmitted to the base station. Simulations show the LEACH can achieve as much as a factor of 8 reduction in energy dissipation compared with conventional outing protocols. In addition, LEACH is able to distribute energy dissipation evenly throughout the sensors, doubling the useful system lifetime for the networks we simulated.

/pdf/energy-efficient-communication-protocol-for-wireless-4vhuagusz2.pdf

Energy-efficient communication protocol for wireless microsensor networks

Wireless distributed microsensor systems will enable the reliable monitoring of a variety of environments for both civil and military applications. In this paper, we look at communication protocols, which can have signicant impact on the overall energy dissipation of these networks. Based on our ndings that the conventional protocols of direct transmission, minimum-transmission-energy, multihop routing, and static clustering may not be optimal for sensor networks, we propose LEACH (Low-Energy Adaptive Clustering Hierarchy), a clustering-based protocol that utilizes randomized rotation of local cluster base stations (cluster-heads) to evenly distribute the energy load among the sensors in the network. LEACH uses localized coordination to enable scalability and robustness for dynamic networks, and incorporates data fusion into the routing protocol to reduce the amount of information that must be transmitted to the base station. Simulations show that LEACH can achieve as much as a factor of 8 reduction in energy dissipation compared with conventional routing protocols. In addition, LEACH is able to distribute energy dissipation evenly throughout the sensors, doubling the useful system lifetime for the networks we simulated.

Energy-efficient communication protocols for wireless microsensor networks

Networking together hundreds or thousands of cheap microsensor nodes allows users to accurately monitor a remote environment by intelligently combining the data from the individual nodes. These networks require robust wireless communication protocols that are energy efficient and provide low latency. We develop and analyze low-energy adaptive clustering hierarchy (LEACH), a protocol architecture for microsensor networks that combines the ideas of energy-efficient cluster-based routing and media access together with application-specific data aggregation to achieve good performance in terms of system lifetime, latency, and application-perceived quality. LEACH includes a new, distributed cluster formation technique that enables self-organization of large numbers of nodes, algorithms for adapting clusters and rotating cluster head positions to evenly distribute the energy load among all the nodes, and techniques to enable distributed signal processing to save communication resources. Our results show that LEACH can improve system lifetime by an order of magnitude compared with general-purpose multihop approaches.

/pdf/an-application-specific-protocol-architecture-for-wireless-1s7y9fiv40.pdf

An application-specific protocol architecture for wireless microsensor networks

Probability Distributions.- Linear Models for Regression.- Linear Models for Classification.- Neural Networks.- Kernel Methods.- Sparse Kernel Machines.- Graphical Models.- Mixture Models and EM.- Approximate Inference.- Sampling Methods.- Continuous Latent Variables.- Sequential Data.- Combining Models.

Pattern Recognition and Machine Learning

Markov decision process for adaptive control of distributed body sensor networks

: In this research project, several issues related to providing Quality of Service (QoS) for command and control applications running on ATM networks were investigated. The QoS requirements are specified in terms of maximum delay, jitter, and cell loss probability. In this context, new AIM switch designs, algorithms for traffic control, routing, and multicasting were developed. Novel neural network based techniques for traffic characterization and admission control at the node and network levels were developed. A new multicast switch architecture was designed for use in high performance ATM networks and its performance as evaluated via simulation. New algorithms for efficiently routing ATM cells in input buffered switches were developed and their performance was evaluated.

Admission Control and Routing Algorithms for ATM Networks

The effect of queueing on a dynamic distributed real-time system, in which jobs have hard deadline requirements, is studied. A job can be guaranteed to be completed before its deadline expires; it is rejected otherwise. An analytic model is presented to calculate the probability that an arbitrary arriving job will be guaranteed. An embedded Markov chain is first established, followed by a probability analysis. In the model, only one copy of the resource is considered. If more than one copy exists in the distributed real-time system, the scheduling discipline for incoming jobs among these copies will affect the probability that a job can be guaranteed. It is shown that a round-robin scheduling, in which arriving jobs are assigned to all the copies of the resource in a cyclic order, is the best strategy. In this strategy, a job that cannot be guaranteed by its assigned copy can never be guaranteed by other copies either. However, it requires a centralized controller to assign the load. The performance issue for cases with multiple copies of a resource is noted with respect to various strategies. The model is nevertheless useful for further research where multiple copies will be taken into account or for the design of a real-time system where jobs with a hard deadline requirement arrive to the system dynamically and nonperiodically. >

Queueing analysis in dynamic distributed real-time systems

Summer Research Program For Meaningful International Experience

This dissertation addresses the problem of assigning connections in interconnection networks. Connection-assignment problem in two different classes of systems is investigated. In a system of the first class, processors are interconnected using a one-sided crosspoint switching network. In this system, we study the problem of assigning connections when faulty crosspoints exist in the network. We provide a complete characterization of the faulty crosspoint networks that can operate in the nonblocking mode. We show that the one-sided crosspoint networks can tolerate as many as 50 percent faulty crosspoints in the rearrangeable mode of operation. Realizing a connection set on a crosspoint network in the presence of an arbitrary fault-set is modeled as a graph matching problem. Two special distributions of faults, namely rectangular and trapezoidal, which allow easy determination of the rearrangeability are also investigated. All results derived in the context of one-sided crosspoint networks are extended to the case of multiple-bus systems.
The second class of systems that we consider consists of satellite-switched time-division multiple access (SS/TDMA) systems. Hierarchical switching systems (HSS's) and SS/TDMA systems with variable bandwidth beams are two examples of these systems. We provide efficient algorithms for connection assignment using optimal number of time-slots in these switching systems. We design sequential, parallel and incremental-sequential algorithms for time-slot assignment (TSA) in these switching systems. Our sequential algorithms are asymptotically faster than the existing sequential algorithms, while parallel algorithms for the TSA problem are proposed for the first time in this dissertation. Our sequential and parallel algorithms are based on modeling the TSA problem as the problem of finding a series of maximum-flows in networks. The incremental-sequential algorithm that we design is shown to achieve considerable speed-up over the other algorithms, when traffic demands in consecutive frames overlap to a significant extent. (Copies available exclusively from Micrographics Department, Doheny Library, USC, Los Angeles, CA 90089-0182.)

Cauligi S. Raghavendra

Papers

Markov decision process for adaptive control of distributed body sensor networks

Admission Control and Routing Algorithms for ATM Networks

Queueing analysis in dynamic distributed real-time systems

Summer Research Program For Meaningful International Experience

Efficient algorithms for connection assignment in interconnection networks