In this study, we discuss how to provide low-delay peer-to-peer streaming with high video quality by considering mesh design with backup parents. To achieve robustness against peer churns, each peer has a certain numb...
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In this study, we discuss how to provide low-delay peer-to-peer streaming with high video quality by considering mesh design with backup parents. To achieve robustness against peer churns, each peer has a certain number of streaming parents and backup parents. We have designed a distributed algorithm that constructed a low-delay mesh and at the same time achieved a certain stream continuity for the peers. We have conducted extensive simulations to study the performance of our algorithms. The results show that our distributed algorithm achieves a lower source-to-peer delay as compared with a traditional scheme. Our results have shown that peer-to-peer live streaming can be delivered in short delays while providing a high level of quality, despite peer churns and the lack of a centralized planner.
In this paper, we propose two snap-stabilizing distributed algorithms for the committee coordination problem. In this problem, a committee consists of a set of processes and committee meetings are synchronized, so tha...
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In this paper, we propose two snap-stabilizing distributed algorithms for the committee coordination problem. In this problem, a committee consists of a set of processes and committee meetings are synchronized, so that each process participates in at most one committee meeting at a time. Snap-stabilization is a versatile technique allowing to design algorithms that efficiently tolerate transient faults. Indeed, after a finite number of such faults (e.g. memory corruptions, message losses, etc), a snap-stabilizing algorithm immediately operates correctly, without any external intervention. We design snap-stabilizing committee coordination algorithms enriched with some desirable properties related to concurrency, (weak) fairness, and a stronger synchronization mechanism called 2-Phase Discussion Time. From previous papers, we know that (1) in the general case, (weak) fairness cannot be achieved in the committee coordination, and (2) it becomes feasible provided that each process waits for meetings infinitely often. Nevertheless, we show that even under this latter assumption, it is impossible to implement a fair solution that allows maximal concurrency. Hence, we propose two orthogonal snap-stabilizing algorithms, each satisfying 2-phase discussion time, and either maximal concurrency or fairness. The algorithm implementing fairness requires that every process waits for meetings infinitely often. Moreover, for this algorithm, we introduce and evaluate a new efficiency criterion called the degree of fair concurrency. This criterion shows that even if it does not satisfy maximal concurrency, our snap-stabilizing fair algorithm still allows a high level of concurrency.
This paper presents the concept of incremental traceback for determining changes in the trace of a network as it evolves with time. A distributed algorithm, based on the methodology of algebraic traceback developed by...
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ISBN:
(纸本)9781424478903
This paper presents the concept of incremental traceback for determining changes in the trace of a network as it evolves with time. A distributed algorithm, based on the methodology of algebraic traceback developed by Dean et al., is proposed that can determine a path of d nodes using O(d) marked packets, and subsequently determine the changes in it using O(log d) marked packets. The algorithm is established to be order-wise optimal, i.e. no other distributed algorithm can determine changes in the path topology using lesser order of bits (or marked packets). The algorithm is shown to have a computational complexity of O(d log d), which is significantly less than that of any existing non-incremental algorithm for algebraic traceback. The extension of the traceback mechanism to systems deploying network coding is also considered.
Core decomposition has been applied widely in the visualization and analysis of massive networks. However, existing studies of core decomposition were only limited to non-temporal graphs, while many real-world graphs ...
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Core decomposition has been applied widely in the visualization and analysis of massive networks. However, existing studies of core decomposition were only limited to non-temporal graphs, while many real-world graphs can be naturally modeled as temporal graphs (e.g., the interaction between users at different time in online social networks, the phone call or messaging records between friends over time, etc.). In this paper, we define the problem of core decomposition in a temporal graph, propose efficient distributed algorithms to compute the cores in massive temporal graphs, and discuss how the technique can be used in temporal graph analysis.
Bandwidth trading schemes give peers an incentive to provide upload bandwidth to other peers in a P2P network for fast file distribution. A popular example is the tit-for-tat strategy used in the BitTorrent protocol. ...
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Bandwidth trading schemes give peers an incentive to provide upload bandwidth to other peers in a P2P network for fast file distribution. A popular example is the tit-for-tat strategy used in the BitTorrent protocol. Although this game theoretical scheme provides an incentive to peers to contribute resources to the network it does not prevent unfairness and the performances of peers vary considerably. Therefore, we propose two new trading schemes, which are based on pricing. One uses explicit price information whereas the other scheme uses the download rates from other peers as the price. For both distributed algorithms the stable point provides a fair resource allocation as well as a Nash equilibrium, i.e. fairness is preserved although peers behave selfishly and try to maximise their own download rates only. We compare both pricing schemes with BitTorrent in simulations of static and dynamic networks. The pricing algorithms outperform BitTorrent with respect to fairness. With explicit prices the download rates converge faster to the fair equilibrium than with implicit ones
In this paper, we propose a joint relay selection and power allocation algorithm for a multi-user, multi relay cellular network using decode-and-forward cooperation strategy with imperfect knowledge of channels. The o...
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In this paper, we propose a joint relay selection and power allocation algorithm for a multi-user, multi relay cellular network using decode-and-forward cooperation strategy with imperfect knowledge of channels. The objective is to minimize the total uplink power of the network taking each user's target data rate as the quality of service constraint under imperfect channel state information (CSI), assuming some statistical knowledge is known about the channel estimation error. Joint relay selection and power allocation is a mixed integer programming problem which is combinatorially hard. For that an efficient sub-optimal solution with low complexity using convex relaxation approach is proposed. After relay selection, a centralized power allocation scheme is developed to optimally allocate the power among the users and the selected relay nodes. Then a low-complexity distributed algorithm is proposed based on a standard primal decomposition approach, where each selected relay can independently minimize its own power. Numerical results demonstrate the effectiveness of the proposed algorithms.
The authors consider a situation in which two processors P/sub 1/ and P/sub 2/ are to evaluate one or more functions f/sub 1/, . . ., f/sub s/ of two vector variables x and y, under the assumption that processor P/sub...
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The authors consider a situation in which two processors P/sub 1/ and P/sub 2/ are to evaluate one or more functions f/sub 1/, . . ., f/sub s/ of two vector variables x and y, under the assumption that processor P/sub 1/ (respectively, P/sub 2/) has access only to the value of x (respectively, y) and the functional form of f/sub 1/, . . ., f/sub s/. They consider a continuous model of communication whereby real-valued messages are transmitted, and they study the minimum number of messages required for the desired computation. Tight lower bounds are established for the following three problems: (1) each f/sub i/ is a rational function and only one-way communication is allowed. (2) The variables x and y are matrices and the processors wish to solve the linear system (x+y)z=b for the unknown z. (3) The processors wish to evaluate a particular root of the polynomial equation Sigma (x/sub i/+y/sub i/)z/sup i/=0, where the sum is from i=0 to n-1.< >
The I/O automation model of N.A. Lynch and M.R. Tuttle (1987) is extended to allow modeling of shared memory systems, as well as systems that include both shared memory and shared action communication. A full range of...
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The I/O automation model of N.A. Lynch and M.R. Tuttle (1987) is extended to allow modeling of shared memory systems, as well as systems that include both shared memory and shared action communication. A full range of types of atomic accesses to shared memory is allowed, from basic reads and writes to read-modify-write. The extended model supports system description, verification, and analysis. As an example, E.W. Dijkstra's (1965) classical shared memory mutual exclusion algorithm is presented and proven correct.< >
In this paper, we present a new "spatiotemporal multicast" protocol for supporting applications which require spatiotemporal coordination in sensornets. To simultaneously consider the factors of moving speed...
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ISBN:
(纸本)0780389387
In this paper, we present a new "spatiotemporal multicast" protocol for supporting applications which require spatiotemporal coordination in sensornets. To simultaneously consider the factors of moving speed and direction, this work mainly investigates a new mobicast routing protocol, called variant-egg-based mobicast (VE-mobicast), by utilizing the variant-egg shape of the forwarding zone to achieve a high predicted accuracy. The contributions of our protocol are summarized as follows: (1) it builds a new shape of a forwarding zone, called the variant-egg, to adaptively and efficiently determine the location and shape of the forwarding zone to maintain the same number of wake-up sensor nodes; (2) it is a fully distributed algorithm which reduces the communication overhead of determining the forwarding zone and the mobicast message forwarding overhead; (3) it can improve the predicted accuracy of the forwarding zone by considering the factors of moving speed and direction. Finally, the simulation results illustrate the performance achievements, compared to existing mobicast routing protocols.
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