Topology design for on-demand dual-path routing in wireless networks

Embarrassingly parallel Grid applications require no inter-worker interaction. Thus, the underlying communication infrastructure is based on the simple but well understood client/server execution model. This is no longer sufficient if more demanding parallel applications that require true Peer-to-Peer interaction are to be deployed on Grids. In this paper, we propose the industrial-strength eXtensible Messaging and Presence Protocol (XMPP) as a network substrate for these non-trivial Peer-to-Peer Grid Computing applications.

Many application scenarios envisioned as part of the ‘Smarter’ Grid depend on an effective underlying communication infrastructure for power distribution. To this end, a linear chain wireless communication architecture is proposed in this work to meet communication requirements at the distribution level of the power grid. A theoretical study is done to understand the capacity limitations of using such linear chain wireless technologies at the distribution level. The application of advanced metering infrastructure (AMI) that encourages customer participation in energy delivery is used as a case study to understand the implications of any limitations imposed by the proposed communication architecture.

This paper outlines a software architecture where zero-copy operations are used comprehensively at every processing point from the Application layer to the Physical layer. The proposed architecture is being used during feasibility studies on advanced networking technologies for the CMS experiment at CERN. The design relies on a homogeneous peer-to-peer message passing system, which is built around memory pool caches allowing efficient and deterministic latency handling of messages of any size through the different software layers. In this scheme portable distributed applications can be programmed to process input to output operations by mere pointer arithmetic and DMA operations only. The approach combined with the open fabric protocol stack (OFED) allows one to attain near wire-speed message transfer at application level. The architecture supports full portability of user applications by encapsulating the protocol details and network into modular peer transport services whereas a transparent replacement of the underlying protocol facilitates deployment of several network technologies like Gigabit Ethernet, Myrinet, Infiniband etc. Therefore, this solution provides a protocol-independent communication framework and prevents having to deal with potentially difficult couplings when the underlying communication infrastructure is changed. We demonstrate the feasibility of this approach by giving efficiency and performance measurements of the software in the context of the CMS distributed event building studies.

Recent developments in virtualization and communication technologies have transformed the way data centers are designed and operated by providing new tools for better sharing and control of data center resources. In particular, Virtual Machine (VM) migration is a powerful management technique that gives data center operators the ability to adapt the placement of VMs in order to better satisfy performance objectives, improve resource utilization and communication locality, mitigate performance hotspots, achieve fault tolerance, reduce energy consumption, and facilitate system maintenance activities. Despite these potential benefits, VM migration also poses new requirements on the design of the underlying communication infrastructure, such as addressing and bandwidth requirements to support VM mobility. Furthermore, devising efficient VM migration schemes is also a challenging problem, as it not only requires weighing the benefits of VM migration, but also considering migration costs, including communication cost, service disruption, and management overhead. This chapter provides an overview of VM migration benefits and techniques and discusses its related research challenges in data center environments. Specifically, the authors first provide an overview of VM migration technologies used in production environments as well as the necessary virtualization and communication technologies designed to support VM migration. Second, they describe usage scenarios of VM migration, highlighting its benefits as well as incurred costs. Next, the authors provide a literature survey of representative migration-based resource management schemes. Finally, they outline some of the key research directions pertaining to VM migration and draw conclusions.

Systems deployed in mobile environments are typically characterized by intermittent connectivity and asynchronous sending/reception of data. To create effective mobile systems for such environments, it is essential to guarantee acceptable levels of timeliness between sending and receiving mobile users. In order to provide QoS guarantees in different application scenarios and contexts, it is necessary to model the system performance by incorporating the intermittent connectivity. Queueing Network Models (QNMs) offer a simple modeling environment, which can be used to represent various application scenarios, and provide accurate analytical solutions for performance metrics, such as system response time. In this paper, we provide an analytical solution regarding the end-to-end response time between users sending and receiving data by modeling the intermittent connectivity of mobile users with QNMs. We utilize the publish/subscribe (pub/sub) middleware as the underlying communication infrastructure for mobile users. To represent the user's connections/disconnections, we model and solve analytically an ON/OFF queueing system by applying a mean value approach. Finally, we validate our model using simulations with real-world workload traces. The deviations between the performance results foreseen by the analytical model and the ones provided by the simulator are shown to be less than 5% for a variety of scenarios.

Nowadays, the increasing penetration of renewable energies often leads to system frequency variation due to the intermittent outputs, which limits the utilization of renewable electricity and brings higher requirements to frequency regulation. Aggregated electric vehicles (EVs) are suggested to be used as good regulation resources because of the vehicle-to-grid (V2G) capability and quick response characteristic. However, the participation of EVs inevitably leads to cyber delays due to their underlying communication infrastructure and scheduling, which may cause instability. To guarantee the system stability, this paper investigates the stability of a grid frequency regulation system with electric vehicle (EV) aggregators embedded by cyber delays in the cyber system. A comprehensive stability assessment method is proposed in this paper based on the discrete spectrum iteration. A stability assessment method flow is designed with only five stages: 1) system initialization and modeling; 2) spectrum transformation; 3) Chebyshev discretization; 4) Krylov subspace projection dimension reduction; 5) Newton correction. Comprehensive case studies are performed on the cyber regulation systems with single, double, and three EV aggregators to extract the stability region and to validate the proposed approach. It is revealed that the controller gain, the ratio between the participation ratios of each aggregator, and that between EV and grid are important factors for determining the stability of the regulation system at a given controller gain. Besides, the criterion of the stability region changing with the three factors is proposed. It is found that the mass utilization of electric vehicles in the frequency control disrupts system stability due to the aggregation delay and thus the stability region can be divided into several intervals and presents periodicity. It is expected that the proposed criteria can help to guide the determination of delay requirements for EV aggregators participating in frequency regulation service.

The emerging area of (smart) Cyber Physical Systems (sCPS) triggers demand for new methods of design, development, and deployment of architecturally dynamic distributed systems. Current approaches (e.g. Component-Based Software Engineering and Agent-Based Development) become insufficient since they fail in addressing challenges specific to sCPS such as mobility, heterogeneous and unreliable deployment infrastructure, and architectural dynamicity. The strong dependence on the underlying communication infrastructure, often combining ad-hoc established links typical for wireless connectivity with more reliable connections of infrastructural networks, requires a novel method to optimize system deployment. In this paper we propose such a method based on the domain knowledge elicited from design level specification. As a proof of concept, we have provided an extension to the DEECo (Dependable Emergent Ensembles of Components) model and validated it on a scenario from the domain of Vehicular Area Networks.

In order to network small satellite constellations for Earth observation and communication, several limitations must be addressed, including distributed topology management, slow down-link data-rates, and single point-to-point communication. Since distributed satellite constellations exacerbate the severity of these limitations, thorough analysis of a constellation's network performance is required to ensure that task objectives are achievable. In this paper, we designed network topologies using Satellite Toolkit (STK) for two low Earth orbit (LEO) Earth observing small satellite constellations: a sun-synchronous repeating ground track constellation and a flower (an elliptical repeating ground track) constellation. Both constellations include six sink satellites that provide a high speed down-link relay point to a ground station. We compared the constellations' inter-satellite links and down-links with respect to network metrics including access window time, drop-ratio, and throughput. We evaluated these network metrics using the Network Simulator (ns-2). Though previous works have proposed sun-synchronous and flower small satellite constellations for Earth observation, these constellations have not been analyzed for these network metrics. Results show that the sun-synchronous constellation with a repeating ground track outperforms the flower constellation with respect to more access time, lower drop-ratio, and higher throughput. Additionally, our simulations determined the optimum media access control slot time and packet transmission intervals for long distance satellite links. Further, our method of designing satellite constellation topologies in STK and exporting them to ns-2 can be used for future studies on any desired constellation network performance evaluations.

Reservation-based wireless TDMA networks can provide deterministic quality-of-service guarantees to multi-hop data flows. The challenge is to route the flows and schedule appropriate transmission slots in a resource-efficient way. In this paper, we study the fundamental question whether multi-path routing, i.e. concurrent use of multiple paths for transmission of data belonging to the same flow, may yield better solutions to the joint routing and slot scheduling problem than single-path routing approaches. To answer this question, we first define an accurate network model. We then devise a branch-and-bound algorithm that computes optimal multi-path and single-path solutions to the joint routing and slot scheduling problem. We apply the algorithm to a large number of scenarios in randomly generated networks and compare optimal network load and end-to-end delay metric values in order to quantify the benefit of multi-path routing over the single-path approach. Our results show that in the studied settings, it is quite rare for multi-path solutions to surpass the optimal single-path solution. Multi-path routing should therefore not be considered an option to improve performance in reservation-based TDMA networks with random topologies.

InWireless Mesh Networks (WMNs), the achievable performance of the nodes depends on the behavior of intermediate routers. Utilizing cognition in the network could result in higher adaptivity to satisfy the end-user requirements. In this paper, we propose a cognitive WMN that utilizes multiple gateways to serve a client through multi-path routing. The injected intellectuality in the network (cognitive process) relieves the capriciousness by adaptively selecting the set of gateways, paths and their data rate contribution. The cognitive technique constantly observes the network through a feedback loop, takes appropriate decision using Game Theory, and applies the decision to the network. For evaluation, extensive simulation is carried out in OMNET discrete event simulator and subsequent results validated the performance of the proposed work.

UAV-Assisted Multi-path Parallel Routing for mmWave-Based Wireless Networks

Nodes in a multi-hop wireless network rely on each other to maintain network connectivity. A primary design objective of these networks is to eliminate or minimize the unavailability of network at some point. However, the movement of nodes creates service disruption and delay as path failure detection and re-establishment consume considerable amount of time. Existing solutions for link classification and prediction operate on discrete values resulting in performance degradation. This problem can best be modelled using fuzzy logic. This work presents a new fuzzy logic based link status classification mechanism for the use with multipath routing protocols in multi-hop wireless networks. The new Enhanced Adhoc On-demand Multipath Distance Vector (eAOMDV) uses fuzzy logic to classify the link status as active, about-to-break or broken. On the basis of fuzzy input parameters RSSI, velocity, distance and bit error rate, the fuzzy based classification mechanism predicts in advance that a particular link, on the active path between the sender and receiver, is about-to-break and helps the reactive multipath routing protocol to start the rerouting operation, thus minimizing the service disruption time, route discovery frequency, end-to-end delay and the packet loss.

Quantum communication networks—the substrate of a future quantum Internet—demand analytical tools that account for entanglement, fidelity, and quantum-specific constraints absent from classical models. In this paper, we introduce the Quantum Network Science (QNS) framework that adapts core network metrics to the quantum setting through fidelity-, success-probability-, and capacity-aware weighting. We formalize centrality (including Quantum PageRank and continuous-time quantum-walk variants), community structure on entanglement graphs, and robustness/percolation with fidelity thresholds. The framework is validated via analytic motifs and controlled simulations on Erdős–Rényi, scale-free, and small-world topologies, as well as satellite-assisted versus fiber-only designs. Our results show that (i) fidelity weighting reorders structural importance and can reconnect networks that appear fragmented classically; (ii) heavy-tailed degree patterns improve tolerance to random failures but heighten vulnerability to targeted hub attacks; (iii) small-world shortcuts induced by long-range quantum links shrink path lengths; and (iv) overlapping “connected components” emerge from entanglement swapping, motivating revised connectivity baselines. We also discuss design implications—degree caps and hub hardening, link-type diversity, multipath routing, and buffering policies—and outline extensions to temporal and multilayer modeling that couple the quantum plane with its classical control layer. QNS thus offers a principled, measurement-oriented foundation for analyzing, comparing, and engineering resilient, high-capacity quantum networks.

Mobile ad hoc networks (MANETs) are self-configured networks without any infrastructure-based network. The mobile nodes (MNs) are continuously deployed in an infrastructure-based network, whereas infrastructure-less network MNs are placed at random positions with mobility, i.e., movements of MNs. The major problem of ad hoc networks is routing and mobility of a node between the source and destination of a node. Due to the high movement in a wireless network, the MNs are not able to establish the connection between source and destination nodes. The network performances measures such as bandwidth and delay which are often changed due to MNs mobility, i.e., these network metrics include inconsistencies in a wireless ad hoc network. The uncertainties create a problem in the choice of the best route from the origin node to the recipient node unit. In this work, fuzzy mobility (FM) is used to resolve the issue of routing and mobility for better route selection in a wireless network. The performance results compared with the well-known existing wireless ad hoc routing protocols based on the packet delivery ratio (PDR), delay and throughput metrics. A fuzzy mobility-based selection gives better results when compared to other mobility models such as Random Way Point (RWP) and Random Direction (RD).KeywordsAd hoc networkFuzzyMobilityRouting first section

Objectives: Wireless Mesh Network is a promising technology in delivering the last mile broadband access. The smart routing technique has been defined during this paper for mesh networks with path selection along the connectivity hole avoidance using pushback mechanism. This paper also deploys a load balancing algorithm among the best paths available. The new design also incorporates the multi-channel triangulation method for the purpose of the optimal path selection among the multiple options. Energy aware routing mechanism is also deployed for evaluating the energy consumed during this network. Methods: The mesh network topology with 120 mesh network nodes deployed randomly over the given area of 100 x 100 meters in order to simulate the multiple networks zones. The network has been majorly divided into the three major zones in order to depict the mesh network zones, which are signified with the different colors in the given topology. The initial connectivity is entirely based upon the transmission radius of the nodes, which keeps the initial connectivity module in to the one-hop connections formation. Findings: The planned methodology compares with the existing routing scheme of Delaunay Triangulation. The performance parameters which compared with existing technique are average distance stretch and packet drop ratio. In this paper, other evaluation metrics are determined which are throughput, latency, number of aggregators and energy consumption. Novelty of the Study: The experimental observations have shown that planned routing mechanism outperforms to other existing scheme in terms of average distance stretch and packet drop ratio. Keywords: Connectivity Hole Avoidance, Distance Stretch, Load Balanced Routing, Multipath Routing