BANDWIDTH EFFICIENT FORMATION OF BROADCAST NETWORK WITH MULTIPLE DESCRIPTION CODING

In this paper, we consider the delay and fault-tolerance of data  broadcasting in  Internet of Things (IoT) networks,  in  which  nodes  form  a network  topology to deliver  live data  from  a source  to the  end receivers. We first consider to build a Small Height Tree which gives an overlay  with small expected  end-to-end  delay. The end-to-end delay and the fault-tolerance can be improved by  adopting  appropriate topology  for  the  overlay  according  to the  characteristics of providers.   Efficient and fault-tolerant in service level agreement (SLA) guaranteed services can hardly be achieved solely by tree or mesh. By multiple-path data  delivery with  multiple  description coding,  service  operators can  use the scheme  to predict  the  amount  of resources to be acquired,  and hence the cost, from  the network

Energy-Latency Tradeoff for In-Network Function Computation in Random Networks

The problem of designing policies for in-network function computation with minimum energy consumption subject to a latency constraint is considered. The scaling behavior of the energy consumption under the latency constraint is analyzed for random networks, where the nodes are uniformly placed in growing regions and the number of nodes goes to infinity. The special case of sum function computation and its delivery to a designated root node is considered first. A policy which achieves order-optimal average energy consumption in random networks subject to the given latency constraint is proposed. The scaling behavior of the optimal energy consumption depends on the path-loss exponent of wireless transmissions and the dimension of the Euclidean region where the nodes are placed. The policy is then extended to computation of a general class of functions which decompose according to maximal cliques of a proximity graph such as the $k$-nearest neighbor graph or the geometric random graph. The modified policy achieves order-optimal energy consumption albeit for a limited range of latency constraints.Comment: A shorter version appears in Proc. of IEEE INFOCOM 201

Protocols for collaborative applications on overlay networks.

Third, we address the limitations of traditional multicasting models. Towards this, we propose a model where a source node has different switching time for each child node and the message arrival time at each child depends on the order in which the source chooses to send the messages. This model captures the heterogeneous nature of communication links and node hardware on the overlay network. Given a multicast tree with link delays and generalized switching delay vectors at each non-leaf node, we provide an algorithm which schedules the message delivery at each non-leaf node in order to minimize the delay of the multicast tree.First, we consider the floor control problem wherein the participating users coordinate among themselves to gain exclusive access to the communication channel. To solve the floor control problem, we present an implementation and evaluation of distributed Medium Access Control (MAC) protocols on overlay networks. As an initial step in the implementation of these MAC protocols, we propose an algorithm to construct an efficient communication channel among the participating users in the overlay network. We also show that our implementation scheme (one of the first among decentralized floor control protocols) preserves the causal ordering of messages.Our research is focused on the development of algorithms for the construction of overlay networks that meet the demands of the distributed applications. In addition, we have provided network protocols that can be executed on these overlay networks for a chosen set of collaborative applications: floor control and multicasting. Our contribution in this research is four fold.Fourth, we address the problem of finding an arbitrary application designer specific overlay network on the Internet. This problem is equivalent to the problem of subgraph homeomorphism and it is NP-Complete. We have designed a polynomial-time algorithm to determine if a delay constrained multicasting tree (call it a guest) can be homeomorphically embedded in a general network (call it a host). A delay constrained multicasting tree is a tree wherein the link weights correspond to the maximum allowable delay between the end nodes of the link and in addition, the link of the guest should be mapped to a shortest path in the host. Such embeddings will allow distributed application to be executed in such a way that application specific quality-of-service demands can be met. (Abstract shortened by UMI.)Second, we address the problem of designing multicasting sub-network for collaborative applications using which messages are required to arrive at the destinations within a specified delay bound and all the destinations must receive the message from a source at 'approximately' the same time. The problem of finding a multicasting sub-network with delay and delay-variation bound has been proved to be NP-Complete in the literature and several heuristics have been proposed

Approximation and Heuristic Algorithms for Minimum Delay Application-Layer Multicast Trees

In this paper we investigate the problem of finding minimum delay application-layer multicast trees, such as the trees constructed in overlay networks. It is accepted that shortest path trees are not a good solution for the problem since such trees can have nodes with very large degree, termed high load nodes. The load on these nodes makes them a bottleneck in the distribution tree, due to computation load and access link bandwidth constrains. Many previous solutions limited the maximal degree of the nodes by introducing arbitrary constraints. In this work, we show how to directly map the node load to the delay penalty at the application host, and create a new model that captures the trade offs between the desire to select shortest path trees and the need to constraint the load on the hosts

Approximation and heuristic algorithms for minimum delay application-layer multicast trees

Abstract—In this paper we investigate the problem of finding minimum-delay application-layer multicast trees, such as the trees constructed in overlay networks. It is accepted that shortest path trees are not a good solution for the problem since such trees can have nodes with very large degree, termed high-load nodes. The load on these nodes makes them a bottleneck in the distribution tree, due to computation load and access link bandwidth constraints. Many previous solutions limited the maximum degree of the nodes by introducing arbitrary constraints. In this work, we show how to directly map the node load to the delay penalty at the application host, and create a new model that captures the trade offs between the desire to select shortest path trees and the need to constrain the load on the hosts. In this model the problem is shown to be NP-hard. We therefore present an approximation algorithm and an alternative heuristic algorithm. Our heuristic algorithm is shown by simulations to be scalable for large group sizes, and produces results that are very close to optimal. Index Terms—Approximation algorithms, overlay networks, peer-to-peer communications. I

Towards self-optimizing frameworks for collaborative systems

Two important performance metrics in collaborative systems are local and remote response times. For certain classes of applications, it is possible to meet response time requirements better than existing systems through a new system without requiring hardware, network, or user-interface changes. This self-optimizing system improves response times by automatically making runtime adjustments to three aspects of a collaborative application. One of these aspects is the collaboration architecture. Previous work has shown that dynamically switching architectures at runtime can improve response times; however, no previous work performs the switch automatically. The thesis shows that (a) another important performance parameter is whether multicast or unicast is used to transmit commands, and (b) response times can be noticeably better with multicast than with unicast when transmission costs are high. Traditional architectures, however, support only unicast - a computer that processes input commands must also transmit commands to all other computers. To support multicast, a new bi-architecture model of collaborative systems is introduced in which two separate architectures govern the processing and transmission tasks that each computer must perform. The thesis also shows that another important performance aspect is the order in which a computer performs these tasks. These tasks can be scheduled sequentially or concurrently on a single-core, or in parallel on multiple cores. As the thesis shows, existing single-core policies trade-off noticeable improvements in local (remote) for noticeable degradations in remote (local) response times. A new lazy policy for scheduling these tasks on a single-core is introduced that trades-off an unnoticeable degradation in performance of some users for a much larger noticeable improvement in performance of others. The thesis also shows that on multi-core devices, the tasks should always be scheduled on separate cores. The self-optimizing system adjusts the processing architecture, communication architecture, and scheduling policy based on response time predictions given by a new analytical model. Both the analytical model and the self-optimizing system are validated through simulations and experiments in practical scenarios