82 research outputs found

    Message and time efficient multi-broadcast schemes

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    We consider message and time efficient broadcasting and multi-broadcasting in wireless ad-hoc networks, where a subset of nodes, each with a unique rumor, wish to broadcast their rumors to all destinations while minimizing the total number of transmissions and total time until all rumors arrive to their destination. Under centralized settings, we introduce a novel approximation algorithm that provides almost optimal results with respect to the number of transmissions and total time, separately. Later on, we show how to efficiently implement this algorithm under distributed settings, where the nodes have only local information about their surroundings. In addition, we show multiple approximation techniques based on the network collision detection capabilities and explain how to calibrate the algorithms' parameters to produce optimal results for time and messages.Comment: In Proceedings FOMC 2013, arXiv:1310.459

    Efficient duty cycle MAC protocols for dynamic traffic loads in wireless sensor networks

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    Idle listening is one of the most significant causes of energy consumption in wireless sensor networks (WSNs), and many protocols have been proposed based on duty cycling to reduce this cost. These protocols, either synchronous or asynchronous, are mainly optimized for light traffic loads. A WSN, however, could often experience bursty and high traffic loads, as may happen for example with broadcast or convergecast traffic. In this thesis, I design and evaluate a new synchronous protocol, DW-MAC (Demand Wakeup MAC), and a new asynchronous protocol, RI-MAC (Receiver Initiated MAC), that are both efficient under dynamic traffic loads, including light or heavy loads. I also design and evaluate ADB (Asynchronous Duty-cycle Broadcasting), a new protocol for efficient multihop broadcasting in WSNs using asynchronous duty cycling. DW-MAC introduces a new low-overhead scheduling algorithm that allows nodes to wake up on demand during the Sleep period of an operational cycle and ensures that data transmissions do not collide at their intended receivers; this demand wakeup adaptively increases effective channel capacity as traffic load increases. RI-MAC, instead, uses receiver-initiated transmissions, in which each transmitter passively waits until its intended receiver wakes up and transmits a beacon frame; this technique minimizes the time a sender and its intended receiver occupy the wireless medium to find a rendezvous time for exchanging data. ADB is integrated with RI-MAC to exploit information only available at this layer; rather than treating the data transmission from a node to all of its neighbors as the basic unit of progress for the multihop broadcast. ADB dynamically optimizes the broadcast at the level of transmission to each individual neighbor of a node as the neighbors asynchronously wakeup, avoiding redundant transmissions and transmissions over poor links, and allowing a transmitter to go to sleep as early as possible. In detailed simulation of all three protocols using ns-2, they each substantially outperform earlier competing protocols in terms of reduced energy and latency and increased packet delivery ratio. I also implemented RI-MAC and ADB in a testbed of MICAz motes using TinyOS and further demonstrate the significant performance improvements made over prior protocols

    The Overlapped K-hop (OK) Clustering Algorithm

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    Clustering is a standard approach for achieving efficient and scalable performance in wireless sensor networks. Clustering algorithms are mostly heuristic in nature and aim at generating the minimum number of disjoint clusters. In this report, we formulate the overlapping multi-hop clustering problem as an extension to the k-dominating set problem. Then we propose a fast, randomized, distributed multi-hop clustering algorithm (OK) for organizing the sensors in a wireless sensor network into overlapping clusters with the goal of minimizing the overall communication overhead, and processing complexity. OK assumes a quasi-stationary network where nodes are location-unaware and have equal significance. No synchronization is needed between nodes. OK is scalable; the clustering formation terminates in a constant time regardless of the network topology or size. The protocol incurs low overhead in terms of processing cycles and messages exchanged. We analyze the effect of different parameters (e.g. node density, network connectivity) on the performance of the clustering algorithm in terms of communication overhead, node coverage, and average cluster size. The results show that although we have overlapped clusters, the OK clustering algorithm still produces approximately equal-sized clusters

    SALAM: A SCALABLE ANCHOR-FREE LOCALIZATION ALGORITHM FOR WIRELESS SENSOR NETWORKS

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    In this dissertation, we present SALAM, a scalable anchor-free protocol for localization in wireless sensor networks. SALAM can determine the positions of sensor nodes without any infrastructure support. We assume that each node has the capability to estimate distances to its corresponding neighbors, that are within its transmission range. SALAM allows to trade the accuracy of the estimated position against node transmission range and/or computational power. The application layer can choose from a whole range of different options, to estimate the sensor node's positions with different accuracy while conserving battery power. Scalability is achieved by dividing the network into overlapping multi-hop clusters each with its own cluster head node. Each cluster head is responsible for building a local relative map corresponding to its cluster using intra-cluster node's range measurements. To obtain the global relative topology of the network, the cluster head nodes collaboratively combine their local maps using simple matrix transformations. In order for two cluster heads to perform a matrix transformation, there must be at least three boundary nodes that belongs to both clusters (i.e. the two clusters are overlapping with degree 3). We formulate the overlapping multi-hop clustering problem and present a randomized distributed heuristic algorithm for solving the problem. We evaluate the performance of the proposed algorithm through analytical analysis and simulation. A major problem with multi-hop relative location estimation is the error accumulated in the node position as it becomes multi-hop away from the cluster head node. We analyze different sources of error and develop techniques to avoid these errors. We also show how the local coordinate system (LCS) affects the accuracy and propose different heuristics to select the LCS. Simulation results show that SALAM achieves precise localization of sensors. We show that our approach is scalable in terms of communication overhead regardless of the network size. In addition, we capture the impact of different parameters on the accuracy of the estimated node's positions. The results also show that SALAM is able to achieve accuracy better than the current ad-hoc localization algorithms

    Routing Protocols for Large-Scale Wireless Sensor Networks: A Review

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    With the advances in micro-electronics, wireless sensor gadgets have been made substantially littler and more coordinated, and large-scale wireless sensor networks (WSNs) based the participation among the noteworthy measure of nodes have turned into a hotly debated issue. "Large-scale" implies for the most part large region or high thickness of a system. As needs be the routing protocols must scale well to the system scope augmentation and node thickness increments. A sensor node is regularly energy-constrained and can't be energized, and in this manner its energy utilization has a very critical impact on the adaptability of the protocol. To the best of our insight, at present the standard strategies to tackle the energy issue in large-scale WSNs are the various leveled routing protocols. In a progressive routing protocol, every one of the nodes are separated into a few gatherings with various task levels. The nodes inside the abnormal state are in charge of data aggregation and administration work, and the low level nodes for detecting their environment and gathering data. The progressive routing protocols are ended up being more energy-proficient than level ones in which every one of the nodes assume a similar part, particularly as far as the data aggregation and the flooding of the control bundles. With concentrate on the various leveled structure, in this paper we give an understanding into routing protocols planned particularly for large-scale WSNs. As per the distinctive goals, the protocols are by and large ordered in light of various criteria, for example, control overhead decrease, energy utilization mitigation and energy adjust. Keeping in mind the end goal to pick up a thorough comprehension of every protocol, we feature their imaginative thoughts, portray the basic standards in detail and break down their points of interest and hindrances. Also a correlation of each routing protocol is led to exhibit the contrasts between the protocols as far as message unpredictability, memory necessities, localization, data aggregation, bunching way and different measurements. At last some open issues in routing protocol plan in large-scale wireless sensor networks and conclusions are proposed

    Routing Protocols for Large-Scale Wireless Sensor Networks: A Review

    Get PDF
    With the advances in micro-electronics, wireless sensor gadgets have been made substantially littler and more coordinated, and large-scale wireless sensor networks (WSNs) based the participation among the noteworthy measure of nodes have turned into a hotly debated issue. "Large-scale" implies for the most part large region or high thickness of a system. As needs be the routing protocols must scale well to the system scope augmentation and node thickness increments. A sensor node is regularly energy-constrained and can't be energized, and in this manner its energy utilization has a very critical impact on the adaptability of the protocol. To the best of our insight, at present the standard strategies to tackle the energy issue in large-scale WSNs are the various leveled routing protocols. In a progressive routing protocol, every one of the nodes are separated into a few gatherings with various task levels. The nodes inside the abnormal state are in charge of data aggregation and administration work, and the low level nodes for detecting their environment and gathering data. The progressive routing protocols are ended up being more energy-proficient than level ones in which every one of the nodes assume a similar part, particularly as far as the data aggregation and the flooding of the control bundles. With concentrate on the various leveled structure, in this paper we give an understanding into routing protocols planned particularly for large-scale WSNs. As per the distinctive goals, the protocols are by and large ordered in light of various criteria, for example, control overhead decrease, energy utilization mitigation and energy adjust. Keeping in mind the end goal to pick up a thorough comprehension of every protocol, we feature their imaginative thoughts, portray the basic standards in detail and break down their points of interest and hindrances. Also a correlation of each routing protocol is led to exhibit the contrasts between the protocols as far as message unpredictability, memory necessities, localization, data aggregation, bunching way and different measurements. At last some open issues in routing protocol plan in large-scale wireless sensor networks and conclusions are proposed
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