K. R. Anupama

A location-based clustering algorithm for data gathering in 3D underwater Wireless Sensor Networks

Wireless sensor networks, whether terrestrial or underwater, usually contain hundreds or in some cases thousands of micro-sensor nodes, that are randomly and densely deployed. In this paper we propose a clustering algorithm based on the geographical location of the sensor nodes for a 3-D hierarchical network architecture called LCAD. An energy model has been proposed and used to analyze the performance of the algorithm.

A Novel Genetic Algorithm for Adaptive Resource Allocation in MIMO-OFDM Systems with Proportional Rate Constraint

This paper considers base station allocation of subcarriers and power to each user to maximize the sum of user data rates, subject to constraints on total power, bit error rate, and proportionality among user data rates in Multiple Input Multiple Output Orthogonal Frequency Division Multiple access (MIMO-OFDMA) system. Previous allocation methods have been iterative nonlinear methods suitable for offline optimization. The subcarrier allocation is tackled using a novel algorithm which combines the aspects of both deterministic and Genetic Algorithms (GA). This modified GA gave very encouraging results as can be seen from the simulation results shown. The simulation results show a marked improvement in the performance of the algorithm as the number of users increase. The capacity attained from the subcarrier allocation scheme generated by our algorithm is found to be comparable to that attained by previous algorithms.

On the use of particle swarm optimization for adaptive resource allocation in orthogonal frequency division multiple access systems with proportional rate constraints

Orthogonal frequency division multiple access (OFDMA) is a promising technique, which can provide high downlink capacity for future wireless systems. The total capacity of OFDMA can be maximized by adaptively assigning subchannels to the user with the best gain for that subchannel, with power subsequently distributed by water-filling algorithm. In this paper we have proposed the use of a customized particle swarm optimization (PSO) aided algorithm to allocate the subchannels. The PSO algorithm is population-based: a set of potential solutions evolves to approach a near-optimal solution for the problem under study. The customized algorithm works for discrete particle positions unlike the classical PSO algorithm which is valid for only continuous particle positions. It is shown that the proposed method obtains higher sum capacities as compared to that obtained by previous works, with comparable computational complexity.

On the use of NSGA-II for multi-objective resource allocation in MIMO-OFDMA systems

This paper investigates the problem of dynamic subcarrier and bit allocation in downlink of Multiple Input Multiple Output (MIMO) Orthogonal Frequency Division Multiple Access (OFDMA) Systems. Using Singular Value Decomposition, the MIMO fading channel of each subcarrier is transformed into an equivalent bank of parallel Single Input Single Output sub-channels. To achieve the capacity bound, one must solve a multiuser subcarrier allocation and the optimal bit allocation jointly. To alleviate the computational complexity of joint subcarrier and bit allocation, several suboptimal solutions have been proposed. These suboptimal solutions handle subcarrier and bits individually. We propose the use of Non-dominated Sorting Genetic Algorithm (NSGA)-II, which is a multi-objective Genetic Algorithm, for joint allocation of bits and subcarriers, in the downlink of MIMO-OFDMA system. NSGA-II is intended for optimization problems involving multiple conflicting objectives. Here the two conflicting objectives are Rate Maximization and Transmit Power Minimization. The simulation results indicate remarkable improvement in terms of convergence over previous approaches involving Evolutionary algorithms. At the same time capacity achieved by the proposed algorithm is found to be comparable with that of previous algorithms.

A wireless sensor network based pipeline monitoring system

This paper proposes a Pipeline Monitoring system using the technology of Wireless Sensor Networks. This research involves the development of a Remote Condition Based Monitoring application for Oil and Gas pipelines using over 100 Wireless Sensor Network Motes. This paper describes the research methodology and a step-wise system development procedure. It starts with the description of an application specific Test Bed for the Pipeline Monitoring System. The subsequent section describes the development of experimental protocols required for designing a Cross-Layered Protocol Stack for the monitoring application. Further, a performance metric based comparative analysis of the experimental protocols is presented giving rise to a high performance and energy efficient Cross-Layered Protocol Stack. This study also includes a short literature survey which conveys the advantages of WSN based Pipeline Monitoring system over contemporary condition based pipeline monitoring systems. The proposed protocol stack consists of Time Synchronization, Routing, Topology Control and Media Access Control protocols. The protocol stack exhibits inherent characteristics of low energy consumption and low memory usage which are vital in the development of a Wireless Sensor Network framework. In addition to this, a user friendly Graphical User Interface for data logging and real time data analysis has also been developed and presented as a part of this study.

Implementation of multi-hop time synchronization on miniature test-bed setup of underwater acoustic sensor network

Time synchronization is an important part of any distributed networked embedded system. It is essentially the process of achieving and maintaining common time base among all network nodes of the system. This task is quite challenging for the systems or applications like sensor networks, since these systems are highly resource constrained, yet need to process time-sensitive data in collaborative manner. Though many protocols have been suggested for terrestrial sensor networks (RSB, TPSN, FTSP and LTS) and they perform reasonably well, very few protocols (THSL, Tri-message) have been suggested for the high-latency underwater acoustic networks, since achieving time-synchronization for high-latency networks is even more challenging issue. Here we describe a very simple extension and implementation of Tri-message time synchronization protocol for multi-hop Underwater Acoustic Sensor Network (UASN) on the miniature test-bed setup.

Cross Layer Best effort QoS aware routing protocol for Ad Hoc Network

Mobile Ad Hoc Networks (MANETs) are a self organizing and adaptive wireless networks. Currently MANETs possess an advanced challenge in providing Quality of Service( QoS) support for real time application data streaming through the network. These applications are delay sensitive and get affected due to congestion in the network. Thus, performance degrades due to high data loss, frequent link breakage and excessive retransmission. The strict layered network structure makes even more difficult to provide solutions for such issues. We propose a protocol which cooperates between adjacent layers and performs cross layer communication. We propose a novel QoS routing for MANET called Cross Layer Best effort QoS aware routing protocol (CLBQ) which considers the metric of link quality, data rates and MAC delay as the QoS parameters. The proposed protocol implements cross layer interaction between PHY, MAC and Network layer. The simulation results conducted shows best effort QoS service to the network in discovering the route and data transfer. Our analysis shows that the protocol has improved throughput and low network overhead.

Cross-layer protocol stack development for three-dimensional underwater Acoustic Sensor Network

Abstract There is a huge interest in the research community to explore the ocean using sensor networks. Various factors such as resource constraints of sensor networks, requirements of applications, properties of underwater acoustic communication and features of ocean environment have a big impact on the design and development of the network architecture as well as the protocol stack. For a long-term deployment of a network, energy efficiency is the most important design criteria. For achieving energy efficiency and overall improvement in network performance, a new approach of cross-layer protocol stack design is being explored by researchers. In this work, a cross-layer protocol stack has been developed for a three-dimensional Underwater Acoustic Sensor Network (UASN) that can be used for a long-term monitoring of ocean column. The proposed stack with cross-layer design combines physical layer, data link layer, network layer protocols along with time-synchronization, clustering and power level management. This protocol stack has been successfully implemented on the UnetSim which is an open source underwater network simulator. In this paper, the details of protocol stack, its implementation on UnetSim along with results and analysis of results have been provided.

Cross layered adaptive cooperative routing mode in mobile ad hoc networks

A Cooperative communication technique has gained considerable attention in the recent time to improve the quality of service (QoS) of ad hoc networks. Cooperative communication significantly improves link capacity through physical layer technique, and spatial diversity gain is achieved by using neighboring nodes to retransmit the overheard information to the intended destination node. However, upper layer protocols are not elegantly designed to adequately exploit the spatial diversity to improve overall network performance in ad hoc networks. Limiting the cooperation to one network layer may not be the best solution. Thus, in this paper, we intend to achieve multilayer functionality from physical layer to the routing layer to provide cooperative communication. An adaptive cross layered cooperative routing algorithm (ACCR) is proposed to analyze the channel state variations and selectively choose the cooperative MAC scheme on demand by exploiting spatial diversity. The algorithm dynamically selects best relay candidates based on QoS metric, contention delay and node energy fairness. Network layer, then chooses an optimized path from source to destination through the selected relay nodes. We validate the algorithm with extensive simulations. The results clearly show that cooperative cross-layer design approach effectively improves the average throughput and average delay for each packet transmission.

FlexEye — A flexible camera mote for sensor networks

In this paper the description of FlexEye - a visual sensor mote suitable of functioning as super node in the static wireless sensor networks is provided. With mobility features added on to FlexEye, the platform can be used as high performance mobile node in mobile wireless sensor networks or as a node in swarm robotics. A comparison of FlexEye with existing camera platforms developed for sensor networks is made on parameters like processing capabilities, power consumption, cost, time to prototype, support for future expansion, etc. The paper elaborates on the custom off the shelf hardware components used in design and the resource pipelined image acquisition technique implemented on the FlexEye mote for acquiring the high resolution images in real time using minimalistic resources. The paper also provides quantitative details on the achieved frame rates and power consumption details of the FlexEye platform.