8394501
Handover Cost Optimization in Traffic Management for Multi-homed Mobile Networks
In this paper, we study the traffic management problem for multi-homed mobile networks with the objective of minimizing the overall handover cost. Two different traffic distribution modes are considered in our study: the Fractional Flow Assignment (FFA) mode which assumes the bandwidth demand from one connection is infinitely splittable and can be assigned to different wireless access networks, and the Integral Flow Assignment (IFA) mode which assumes that at any time the bandwidth demand from each connection can only be assigned to a single wireless network. We show that the general FFA problem and the IFA problem are both NP-hard and propose optimal solutions to the four special cases of the FFA problem and heuristic solutions to the general FFA problem and the IFA problem. Extensive simulations are conducted to verify the impact of the capacity-demand ratio on the performance of the proposed solutions.
4792
Fast Sensor Placement Algorithms for Fusion-Based Target Detection
Mission-critical target detection imposes stringent performance requirements for wireless sensor networks, such as high detection probabilities and low false alarm rates. Data fusion has been shown as an effective technique for improving system detection performance by enabling efficient collaboration among sensors with limited sensing capability. Due to the high cost of network deployment, it is desirable to place sensors at optimal locations to achieve maximum detection performance. However, for sensor networks employing data fusion, optimal sensor placement is a non-linear optimization problem with prohibitive computational complexity. In this paper, we present fast sensor placement algorithms based on a probabilistic data fusion model. Simulation results show that our algorithms can meet the desired detection performance with a small number of sensors while achieving up to 7-fold speedup over the optimal algorithm.
9143022
Data fusion improves the coverage of wireless sensor networks
Wireless sensor networks (WSNs) have been increasingly available for critical applications such as security surveillance and environmental monitoring. An important performance measure of such applications is sensing coverage that characterizes how well a sensing field is monitored by a network. Although advanced collaborative signal processing algorithms have been adopted by many existing WSNs, most previous analytical studies on sensing coverage are conducted based on overly simplistic sensing models (e.g., the disc model) that do not capture the stochastic nature of sensing. In this paper, we attempt to bridge this gap by exploring the fundamental limits of coverage based on stochastic data fusion models that fuse noisy measurements of multiple sensors. We derive the scaling laws between coverage, network density, and signal-to-noise ratio (SNR). We show that data fusion can significantly improve sensing coverage by exploiting the collaboration among sensors. In particular, for signal path loss exponent of k (typically between 2.0 and 5.0), rho_f=O(rho_d^(1-1/k)), where rho_f and rho_d are the densities of uniformly deployed sensors that achieve full coverage under the fusion and disc models, respectively. Our results help understand the limitations of the previous analytical results based on the disc model and provide key insights into the design of WSNs that adopt data fusion algorithms. Our analyses are verified through extensive simulations based on both synthetic data sets and data traces collected in a real deployment for vehicle detection.
17259450
Routing and wavelength assignment for core-based tree in WDM networks
In this paper, we address the routing and wavelength assignment problem for the core-based tree (CBT) service in a wavelength-division-multiplexing (WDM) network, where k sources need to send data to a common core node. We formally model the problem as a problem of finding k shortest lightpaths from sources to the core with the constraint of wavelength collision free. To address different objectives, we define and study several subproblems. For the feasibility and the minimum total cost problems of k shortest lightpaths, we show how the classical network flow algorithms can be modified and applied efficiently on the network flow model constructed on the transformed wavelength graph. For the minimum max-cost and the constrained feasibility problems, we prove their NP-completeness and propose two efficient heuristic algorithms. Simulation results show that the proposed heuristic algorithms achieve performance very close to the calculated lower bounds.
839113
Interference Aware and Delay Bounded Routing in Hybrid Wireless-Optical Access Network
Hybrid Wireless-Optical Access Network (WOAN) is a newly emerged network which integrates passive optical networks (PONs) and wireless mesh neworks(WMNs) to provide the ubiquitous, high bandwidth last mile Internet access. In WOAN, transmission delay for traffic up to the Internet consists of wireless path delay in WMNs and waiting delay at ONUs due to the TDMA schedule. The ONU from which transmission delay is minimal is chosen to be the destination for traffic and the minimal transmission delay is defined as delay bound. In the paper, we intend to find the wireless path to the destinated ONU with path delay no more than delay bound and meanwhile with the minimal maximal link delay, which is defined as Interference Aware and Delay Bounded Routing (IADBR) problem. We propose both centralized and distributed algorithms to solve IADBR. Simulation results show that the distributed algorithm performs quite closely to the optimal centralized algorithm and performs much better than the shortest path algorithm.
1245508
Exploring core based tree (CBT) in WDM networks
In this paper, we explore the routing and wavelength assignment problem for the CBT service in a WDM network where k sources need to send data to a common core node. We formally model the problem as a problem of finding k shortest lightpaths from sources to the core subject to the constraint of wavelength collision free. We define and study several subproblems, each addressing a different objective. For the feasibility and the minimum total cost problems of k shortest lightpaths, we show how the classical network flow algorithms can be modified and applied efficiently on the network flow model constructed on the transformed wavelength graph. For the minimum max-cost problem, we prove its NP-completeness and propose two efficient heuristic algorithms. Simulation results show that the proposed heuristic algorithms perform very close to the calculated lower bounds.
42010730
Cross-layer Routing Design in Cognitive Radio Networks by Colored Multigraph Model
In this paper, the cross-layer design routing in cognitive radio(CR) networks is studied. We propose a colored multigraph based model for the temporarily available spectrum bands, called spectrum holes in this paper. Based on this colored multigraph model, a polynomial time algorithm with complexity O(n2) is also proposed to develop a routing and interface assignment, where n is the number of nodes in a CR network. Our algorithm optimizes the hop number of routing, meanwhile, the adjacent hop interference (AHI) is also optimized locally.
2128602
Programming Overlay Networks with Overlay Sockets
The emergence of application-layer overlay networks has inspired the development of new network services and applications. Research on overlay networks has focused on the design of protocols to maintain and forward data in an overlay network, however, less attention has been given to the software development process of building application programs in such an environment. Clearly, the complexity of overlay network protocols calls for suitable application programming interfaces (APIs) and abstractions that do not require detailed knowledge of the overlay protocol, and, thereby, simplify the task of the application programmer. In this paper, we present the concept of an overlay socket as a new programming abstraction that serves as the end point of communication in an overlay network. The overlay socket provides a socket-based API that is independent of the chosen overlay topology, and can be configured to work for different overlay topologies. The overlay socket can support application data transfer over TCP, UDP, or other transport protocols. This paper describes the design of the overlay socket and discusses API and configuration options. The overlay socket has been used to develop a variety of applications, from multicast-file transfer programs, to multicast video streaming systems.
5372457
Traffic Engineering with AIMD in MPLS Networks
We consider the problem of allocating bandwidth to competing flows in an MPLS network, subject to constraints on fairness, efficiency, and administrative complexity. The aggregate traffic between a source and a destination, called a flow, is mapped to label switched paths (LSPs) across the network. Each flow is assigned a preferred ('primary') LSP, but traffic may be sent to other ('secondary') LSPs. Within this context, we define objectives for traffic engineering, such as fairness, efficiency, and preferred flow assignment to the primary LSP of a flow ('Primary Path First', PPF). We propose a distributed, feedback-based multipath routing algorithm that attempts to apply additive-increase and multiplicative-decrease (AIMD) to implement our traffic engineering objectives. The new algorithm is referred to as multipath-AIMD. We use ns-2 simulations to illustrate the fairness criteria and PPF property of our multipath-AIMD scheme in an MPLS network.