Traditional distributed algorithms for QoS routing in wired networks may not work in the ad-hoc domain, due to interference between links. We propose a heuristic interference-aware QoS routing algorithm (IQRouting) th...
详细信息
Traditional distributed algorithms for QoS routing in wired networks may not work in the ad-hoc domain, due to interference between links. We propose a heuristic interference-aware QoS routing algorithm (IQRouting) that chooses candidate paths based on localized information at the source nodes. The candidate paths are compared in a distributed manner using probe packets, with the best path confirmed by the destination node. Simulations demonstrate significant (up to 30 %) improvements in admission ratio over traditional shortest path algorithms, and better performance than other QoS routing algorithms in literature as well
The average download time of a file is an important performance metric for a user in a peer-to-peer network. We point out that the common approach of analyzing the average download time based on average service capaci...
详细信息
The average download time of a file is an important performance metric for a user in a peer-to-peer network. We point out that the common approach of analyzing the average download time based on average service capacity is fundamentally flawed, and show that spatial heterogeneity and temporal correlation in the service capacity over different paths are the two major factors that have negative impact on the average file download time. We then propose a simple and distributed algorithm that can completely remove this negative impact of the two factors and yield the smallest possible average download time for each user in the network.
The paper targets the problem of optimal resource allocation in overlay multicast, which poses both theoretical and practical challenges. Theoretically, resource allocation among overlay flows is not subject to the ne...
详细信息
The paper targets the problem of optimal resource allocation in overlay multicast, which poses both theoretical and practical challenges. Theoretically, resource allocation among overlay flows is not subject to the network capacity constraint but also the data constraint, mainly due to the dual role of end hosts as both receivers and senders. Practically, existing distributed resource allocation schemes assume the network links to be capable of measuring flow rates, calculating and communicating price signals, none of which actually exists in the Internet today. We address these challenges as follows. First, we formalize the problem using nonlinear optimization theory, which incorporates both network constraint and data constraint. Based on our theoretical framework, we propose a distributed algorithm, which is proved to converge to the optimal point, where the aggregate utility of all receivers is maximized. Second, we propose an end-host-based solution, which relies on the coordination of end hosts to accomplish tasks originally assigned to network links. our solution can be directly deployed without any changes to the existing network infrastructure.
In this paper we provide a parallel algorithm that given any n-node m-edge directed graph and source vertex s computes all vertices reachable from s with Õ(m) work and n {1/2 + o(1) } depth with high probability ...
详细信息
In this paper we provide a parallel algorithm that given any n-node m-edge directed graph and source vertex s computes all vertices reachable from s with Õ(m) work and n {1/2 + o(1) } depth with high probability in n. This algorithm also computes a set of Õ(n) edges which when added to the graph preserves reachability and ensures that the diameter of the resulting graph is at most n {1/2 + o(1) }. Our result improves upon the previous best known almost linear work reachability algorithm due to Fineman [1] which had depth Õ(n 2/3 ). Further, we show how to leverage this algorithm to achieve improved distributed algorithms for single source reachability in the CONGEST model. In particular, we provide a distributed algorithm that given a n-node digraph of undirected hop-diameter D solves the single source reachability problem with Õ(n 1/2 + n 1/3+o(1) D 2/3 ) rounds of the communication in the CONGEST model with high probability in n. Our algorithm is nearly optimal whenever D = O(n 1/4-ε ) for any constant ε > 0 and is the first nearly optimal algorithm for general graphs whose diameter is Ω(n δ ) for any constant δ.
Data and service delivery have been historically based on a ''network centric'' model, with datacentres being the focal sources. The amount of energy consumed by these datacentres has become an emergin...
详细信息
Data and service delivery have been historically based on a ''network centric'' model, with datacentres being the focal sources. The amount of energy consumed by these datacentres has become an emerging issue for the companies operating them. Thus, many contributions have proposed solutions to improve the energy efficiency of current datacentre architecture and deployments. A recently proposed approach argues for removing the datacentres from the delivery architecture. Their functionalities will instead be distributed at the edge of the network, directly within operator-managed home devices, such as Home Gateways, or Set-Top-Box (STB). This paper presents a study of the overall energy consumption required by such a community of STBs in order to provide the same services as datacentres. This paper also investigates a possible distributed algorithm to further reduce this overall energy consumption. This algorithm will be deployed over a managed peer-to-peer network of STBs. It will make optimized decisions and instruct unused STBs to switch Off to save energy without altering the general Service Level Agreement. We demonstrate the potential benefit of such an algorithm through an off-line scheduling. Finally, we propose a service-delivery model that allows us to integrate the service availability in the energy optimization problem. The combination of these two models is the first step in the development of our energy optimisation distributed algorithm.
Dynamic spectrum access (DSA) redistributes spectrum from service providers with spare channels to those in need for them. Existing works on such spectrum exchange mainly focus on double auctions, where an auctioneer ...
详细信息
Dynamic spectrum access (DSA) redistributes spectrum from service providers with spare channels to those in need for them. Existing works on such spectrum exchange mainly focus on double auctions, where an auctioneer centrally enforces a certain spectrum allocation policy. In this paper, we take a different and new perspective, proposing to use matching as an alternative tool to realize DSA in a distributed way for a free market, which consists of only buyers and sellers, but no trustworthy third-party authority. Compared with conventional many-to-one matching problems, the spectrum matching problem is distinctively challenging due to the interference bound between buyers: the same channel can be reused by an unlimited number of non-interfering buyers, but must be exclusively occupied by only one of interfering buyers. In this paper, we firstly formulate the spectrum matching problem as a many-to-one matching with peer effects, i.e., a buyer's utility is affected by other buyers who are matched to the same seller. We then present a two-stage distributed algorithm that converges to an interference-free and Nash-stable matching result. Simulations show that the proposed distributed matching algorithm can achieve 90% of the social welfare from the optimal matching result.
This paper describes a distributed algorithm for reliable multicast in mobile cellular networks. In the proposed solution the multicast message is flooded to all the base stations over reliable channels. The base stat...
详细信息
This paper describes a distributed algorithm for reliable multicast in mobile cellular networks. In the proposed solution the multicast message is flooded to all the base stations over reliable channels. The base stations then collectively ensure that all mobile nodes belonging to the multicast group get the message. The originality of our solution is that it is fully decentralized. Each base station can independently decide when to flush a message from its buffer. Even if a node moves from one cell to another while a multicast is in progress, delivery of the message to the node is guaranteed. Simulation experiments show that using the proposed solution, memory requirements at the base stations are significantly smaller than by using centralized solutions.
It is known that the leader election in anonymous networks is not always solvable, and solvable/unsolvable cases are characterized by the network topologies. Therefore a distributed leader election algorithm is requir...
详细信息
It is known that the leader election in anonymous networks is not always solvable, and solvable/unsolvable cases are characterized by the network topologies. Therefore a distributed leader election algorithm is required to elect a leader when it is possible, otherwise recognize the impossibility and stop. Although former studies proposed several leader election algorithms, the space complexity of the problem is not considered well. This paper focuses on the space complexity, that is, the necessary or sufficient number of bits on processors to execute a leader election algorithm. First we show that only one bit memory is sufficient for a leader election algorithm which is specific to a fixed n. We then show that a general algorithm can solve the leader election for arbitrary n if each processor has O(n log d) bits memory where d is the maximum degree of a processor. Finally, we give a lower bound Omega(log n) on the space complexity, that is, we show that it is impossible to construct a leader election algorithm if only log n bits are available for a processor.
This tutorial examines well-known algorithms for distributed consensus problems, from classical consensus to blockchain consensus. We discuss exact algorithms that are high-level as in pseudocode and directly executab...
详细信息
ISBN:
(数字)9798350354713
ISBN:
(纸本)9798350354720
This tutorial examines well-known algorithms for distributed consensus problems, from classical consensus to blockchain consensus. We discuss exact algorithms that are high-level as in pseudocode and directly executable as programs at the same time, focusing on how to quickly program, configure, run, and check these algorithms as well as distributed algorithms and systems in general.
In this talk, I present the SomeWhere approach and infrastructure for building semantic peer-to-peer data management systems based on simple personalized ontologies but which are distributed at a large scale.
In this talk, I present the SomeWhere approach and infrastructure for building semantic peer-to-peer data management systems based on simple personalized ontologies but which are distributed at a large scale.
暂无评论