A novel computation-efficient quantized distributed optimization algorithm is presented in this article for solving a class of convex optimization problems over time-varying undirected networks with limited communicat...
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A novel computation-efficient quantized distributed optimization algorithm is presented in this article for solving a class of convex optimization problems over time-varying undirected networks with limited communication capacity. These convex optimization problems are usually relevant to the minimization of a sum of local convex objective functions using only local communication and local computation. In most of the existing distributed optimization algorithms, each agent needs to calculate the subgradient of its local convex objective function at each time step, which leads to extremely heavy computation. The proposed algorithm incorporates random sleep scheme into procedures of agents' updates in a probabilistic form to reduce the computation load, and further allows for uncoordinated step-sizes of all agents. The quantized strategy is also applied, which overcomes the limitation of communication capacity. Theoretical analysis indicates that the convex optimization problems can be solved and numerical analysis shows that the computation load of subgradient can be significantly reduced by the proposed algorithm. The boundedness of the quantization levels at each time step has been explicitly characterized. Simulation examples are presented to demonstrate the effectiveness of the algorithm and the correctness of the theoretical results.
We consider the problem of finding a multicast tree rooted at the source node and including all the destination nodes such that the maximum weight of the tree arcs is minimized. It is of paramount importance for many ...
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We consider the problem of finding a multicast tree rooted at the source node and including all the destination nodes such that the maximum weight of the tree arcs is minimized. It is of paramount importance for many optimization problems, e.g., the maximum-lifetime multicast problem in multihop wireless networks, in the data networking community. We explore some important properties of this problem from a graph theory perspective and obtain a min-max-tree max-min-cut theorem, which provides a unified explanation for some important while separated results in the recent literature. We also apply the theorem to derive an algorithm that can construct a global optimal min-max multicast tree in a distributed fashion. In random networks with it nodes and m arcs, our theoretical analysis shows that the expected communication complexity of our distributed algorithm is in the order of 0(m). Specifically, the average number of messages is 2(n - 1 - gamma) - 2ln(n - 1) + m, at most, in which gamma is the Euler constant. To our best knowledge, this is the first contribution that possesses the distributed and scalable properties for the min-max multicast problem and is especially desirable to the large-scale resource-limited multihop wireless networks, like sensor networks.
In Wireless Sensor Networks (WSNs), energy saving techniques are critical for efficient routing. The Connected Dominating Set (CDS) used as a virtual backbone for saving energy in WSN has been extensively studied in t...
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In Wireless Sensor Networks (WSNs), energy saving techniques are critical for efficient routing. The Connected Dominating Set (CDS) used as a virtual backbone for saving energy in WSN has been extensively studied in the past two decades. Since the time complexity and performance ratio are two important metrics to evaluate algorithms, reducing the time expenditure of algorithm and the total number of sensors in CDS are two key problems for CDS construction. In this paper, we propose a novel distributed algorithm, Dominating Set based on Link and Degree and Connecting Tree (LDDS-CT), to find a Minimum CDS (MCDS). LDDS-CT is divided into two phases. In the first phase, a Dominating Set (DS) is constructed using LDDS. In the second phase, a CT algorithm for connecting all sensors in DS is proposed, which can guarantee the number of connectors added to DS is minimized. This paper proves that the time cost of LDDS-CT is at most 2.25n and the performance ratio of LDDS-CT is at most 14.798opt + 9.748, where n is the number of sensors and opt is the size of any MCDS. To the best of our knowledge, LDDS-CT is the fastest two-phased distributed algorithm for MCDS construction with unknown network topology. And the performance ratio of the proposed algorithm is close to the sate-of-the-art algorithms in theory. The simulation results show that LDDS-CT outperforms the existing distributed algorithms. (C) 2018 Elsevier B.V. All rights reserved.
Directional sensor networks (DSNs) are still receiving consideration in different fields of high-level monitoring applications. However, unlike traditional omni-directional sensors, directional sensors are characteriz...
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We propose a Jacobi-style distributed algorithm to solve convex, quadratically constrained quadratic programs (QCQPs), which arise from a broad range of applications. While small to medium-sized convex QCQPs can be so...
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We propose a Jacobi-style distributed algorithm to solve convex, quadratically constrained quadratic programs (QCQPs), which arise from a broad range of applications. While small to medium-sized convex QCQPs can be solved efficiently by interior-point algorithms, high-dimension problems pose significant challenges to traditional algorithms that are mainly designed to be implemented on a single computing unit. The exploding volume of data (and hence, the problem size), however, may overwhelm any such units. In this paper, we propose a distributed algorithm for general, non-separable, high-dimension convex QCQPs, using a novel idea of predictor-corrector primal-dual update with an adaptive step size. The algorithm enables distributed storage of data as well as parallel, distributed computing. We establish the conditions for the proposed algorithm to converge to a global optimum, and implement our algorithm on a computer cluster with multiple nodes using message passing interface. The numerical experiments are conducted on data sets of various scales from different applications, and the results show that our algorithm exhibits favorable scalability for solving high-dimension problems.
We address the joint problem of learning and scheduling in multi-hop wireless network without a prior knowledge on link rates. Previous scheduling algorithms need the link rate information, and learning algorithms oft...
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We address the joint problem of learning and scheduling in multi-hop wireless network without a prior knowledge on link rates. Previous scheduling algorithms need the link rate information, and learning algorithms often require a centralized entity and polynomial complexity. These become a major obstacle to develop an efficient learning-based distributed scheme for resource allocation in large-scale multi-hop networks. In this work, by incorporating with learning algorithm, we develop provably efficient scheduling scheme under packet arrival dynamics without a priori link rate information. We extend the results to distributed implementation and evaluation their performance through simulations.
Maximizing the full coverage lifetime over a predefined set of target points (TPs) is one of the most fundamental functions in wireless sensor networks. However, coverage performance is challenging to maintain due to ...
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Maximizing the full coverage lifetime over a predefined set of target points (TPs) is one of the most fundamental functions in wireless sensor networks. However, coverage performance is challenging to maintain due to the energy consumption of self-contained sensor nodes (SNs). Therefore, in this paper, we propose an energy-efficient distributed algorithm for target-coverage preservation (DATCP) that can rotate a group of SNs for the monitoring task in each time slot based on cover sets and the remaining energy to ensure preservation of coverage. Specifically, we first propose a novel SN clustering algorithm based on the location of the TPs to reduce the number of control messages. Next, we introduce a cover set construction algorithm to group SNs that can cover all TPs in a cluster. In addition, our approach considers the capability of multihop communication to improve the energy efficiency in the network. The results of extensive experiments show that substantial improvements in full coverage lifetime and energy efficiency compared to existing algorithms are obtained by our proposed algorithm: the full coverage lifetime can be enhanced more than 30 % compared to that of other approaches.
In this paper, we present provably-good distributed task assignment algorithms for a heterogeneous multi-robot system, in which the tasks form disjoint groups and there are constraints on the number of tasks a robot c...
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In this paper, we present provably-good distributed task assignment algorithms for a heterogeneous multi-robot system, in which the tasks form disjoint groups and there are constraints on the number of tasks a robot can do (both within the overall mission and within each task group). Each robot obtains a payoff (or incurs a cost) for each task and the overall objective for task allocation is to maximize (minimize) the total payoff (cost) of the robots. In general, existing algorithms for task allocation either assume that tasks are independent or do not provide performance guarantee for the situation, in which task constraints exist. We present a distributed algorithm to provide an almost optimal solution for our problem. The key aspect of our distributed algorithm is that the overall objective is (almost) maximized by each robot maximizing its own objective iteratively (using a modified payoff function based on an auxiliary variable, called price of a task). Our distributed algorithm is polynomial in the number of tasks, as well as the number of robots.
The reconstruction of time-varying signals on graphs is a prominent problem in graph signal processing community. By imposing the smoothness regularization over the time-vertex domain, the reconstruction problem can b...
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The reconstruction of time-varying signals on graphs is a prominent problem in graph signal processing community. By imposing the smoothness regularization over the time-vertex domain, the reconstruction problem can be formulated into an unconstrained optimization problem that minimizes the weighted sum of the data fidelity term and regularization term. In this paper, we propose an approximate Newton method to solve the problem in a distributed manner, which is applicable for spatially distributed systems consisting of agents with limited computation and communication capacity. The algorithm has low computational complexity while nearly maintains the fast convergence of the second-order methods, which is evidently better than the existing reconstruction algorithm based on the gradient descent method. The convergence of the proposed algorithm is explicitly proved. Numerical results verify the validity and fast convergence of the proposed algorithm.
A simple decentralized distributed algorithm for the set intersection problem is presented. This algorithm is an improvement of the previous bound for the problem and uses only 3m(n - 1) + 3(n - 1) messages, where m i...
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A simple decentralized distributed algorithm for the set intersection problem is presented. This algorithm is an improvement of the previous bound for the problem and uses only 3m(n - 1) + 3(n - 1) messages, where m is the cardinality of the smallest-sized subset and n is the number of processors, compared to 5mn + 2n - 4m messages as proposed in a previous solution for the same problem. Our algorithm has a time complexity of O(mn).
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