Small Number Of Hops Research Articles

Load Balancing between Paths using Software Defined Networks

Small networks usually use Ethernet devices that apply solutions such as the Spanning Tree Protocol (STP) to forward packets through a single path with no loops. However, this prevents the use of idle links that may reduce congestion and augment the aggregate bandwidth of the network. This work proposes a load balancing mechanism between paths using Software Defined Networks (SDNs). The proposed mechanism, named MLB (Multipath Load Balance), computes multiple paths with disjoint links that have the smallest number of hops between source and destination. Moreover, MLB has a “switching control” function that verifies whether the current occupation of the path exceeds a percentage of its capacity and if the potential new path computed by MLB has an occupation at least a percentage value smaller than that of the current path. MLB is implemented in Python and evaluated in Mininet. The results show that it is possible to increase the aggregate bandwidth by 95% and decrease the packet loss by about 95.5% compared with the standard operating mode of the OpenDaylight SDN controller.

Parallel Hub Labeling Maintenance With High Efficiency in Dynamic Small-World Networks

Shortest path computation is a fundamental operation in many application domains and is especially challenging in frequently evolving small-world networks (i.e., graphs in which many nodes can be reached from every other node by a small number of hops). Index-based methods, especially ones based on 2-hop labeling are often used for high query efficiency. However, the evolvements of small-world networks in many realistic scenarios pose the challenge of efficient maintenance of the shortest path index. In this work, we adopt the state-of-the-art <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Parallel Shortest-distance Labeling (PSL)</i> as the underlying 2-hop labeling construction method, and design algorithms to support its efficient update given edge weight changes (increase and decrease). Specifically, we focus on weighted <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">PSL (WPSL)</i> and propose a propagation-based update mechanism for both synchronous and asynchronous propagation. We also identify the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">curse of pruning power</i> in the edge weight increase case, and solve it with a balance between index size and effectiveness. Followed by, we extend the asynchronous propagation method to <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Pruned Landmark Labeling (PLL)</i> for faster index maintenance and query processing with a smaller index size. Finally, we further optimize the index performance by reducing the index size through graph contraction and accelerating the index update through parallelized mix index update. Our experimental results on real-life and synthetic networks demonstrate the superiority of our algorithms over the relevant baselines on index maintenance.

Guidance for precision landing on asteroid using active hopping trajectory

In the landing mission on low-gravity asteroids, the probe may have a large position error when touching the surface or hop away from the desired target after a collision. To achieve a precision landing, a guidance method using an active hopping trajectory is proposed. In contrast to passive hopping, the active hopping strategy can reduce the landing errors by controlling the collision attitude sequence of the probe. The collision attitude sequence is determined by dynamically planning the hopping trajectory which consists of an active hopping phase and a braking phase. The active hopping phase achieves an expected range with a small number of hops, and the braking phase eliminates the probe's horizontal velocity and provides feedback for the range adjustment of the active hopping phase. The guidance method based on the hopping trajectory planning is then verified in a simulated asteroid landing scenario. The results show that the method is effective in reducing the landing errors, robust to the environmental parameter perturbations, and applicable to landings on inclined surfaces.

A Novel Virtual-Cluster Based Architecture of Double-Layer Optical Networks-on-Chip

Optical Networks-on-Chip (ONoCs) have been proposed as the most promising solution for on-chip multi-core processors interconnection infrastructure due to its low latency, low power dissipation, and high bandwidth density. In ONoCs, the mesh topology is a typical structure that is regarded as the one of the most primary choice in ONoCs design due to its regular structure, simplicity, and divinable scalability in terms of network performance and budget. However, mesh structure has low connectivity and high insertion loss and crosstalk noise, which severely reduce the energy efficiency and signal reliability. In this paper, we first propose a novel double-layer ONoCs structure based on a partition of Virtual-Cluster in mesh, named VCmesh, which contains two candidate communication modes: inter-cluster communication and non-cluster communication. Furthermore, we design the length-optimized-routing-protocol (LORP) to select the preferred with smaller number of hops. The analyses and simulation results indicate that the performance of the VCmesh network is better than that of the typical mesh structure, especially in terms of end-to-end (ETE) latency and throughput. In physical layer performance, the VCmesh has a higher signal-to-noise-ratio (SNR), which improves the transmission quality of the optical signal. In addition, compared with the typical mesh-based ONoCs, the VCmesh-based ONoCs reduce the minimum required laser output power for 16 nodes, 25 nodes, and 36 nodes by 52.4&#x0025;, 85.6&#x0025;, and 94.6&#x0025;, respectively.

A Naming Game-Based Method for the Location of Information Source in Social Networks

We study herein the problem of the location of the information propagation source in social networks based on the network topology and a set of observations. We propose a concise and novel method to accurately locate the source of information using naming game theory. This study introduces the design of a dynamic deployment method that reduces considerably the number of observations and the time needed to locate the source. Moreover, it calculates the probability of each node that acts as a source based on the information provided by observations. This method can be potentially applied to various information propagation models. The simulation results reveal that the method is able to estimate the information source within a small number of hops from the true source.

Broadcast-based routing protocol for smart lighting systems

We consider a smart lighting system, where sensors and actuators deployed on lamp posts generate data intended for a sink at the end of a street, thus creating a linear wireless network (LWN). We propose a novel broadcast-based routing protocol for this type of networks. During an initial discovery phase each node identifies its neighbours and selects its best neighbour as the one closest to the sink. Data is then transmitted in broadcast, by prioritising the best neighbour as forwarder. The protocol allows packets to reach the sink through a small number of hops and consequently improve throughput and packet delivery probability compared to existing solutions. The proposed protocol has been implemented, tested and compared to standard solutions based on IEEE 802.15.4 and Zigbee. Experimental results, in terms of packet loss rate, throughput and number of hops to reach the sink, show the improvement with respect to the existing solutions.

BBIL: A Bounding-Based Iterative Method for IoT to Localize Things

The Internet of Things (IoT) has become more popular over the past decade. For the IoT to be successful, it is vital to track the location of these things (sensors or actuators). In this article, based on a new IoT underlying architecture, a narrowband-IoT (NB-IoT)-aided, bounding-based iterative and range-free method, named BBIL, is proposed to localize things. We make use of the location information of all anchor regular nodes that can help improve the localization accuracy as much as possible. Specifically, not only single-hop and multihop anchor things but also single-hop and multihop regular things are used for localization. In addition, the communication and computational loads of the local network are greatly decreased because the anchor things can directly access the Internet using the NB-IoT modules; hence, data can be sent to the Internet through a small number of hops in the local network and processed in the cloud/edge computing facilities in a centralized way. To balance the location accuracy and energy consumption of BBIL, we propose a theoretical model to obtain the optimal number of the anchor things. BBIL is evaluated and compared with the existing methods. The simulation results indicate that the average localization error of BBIL is less than 11.6%. Also, it performs well in anisotropic networks. In addition, we verified the validity of our method in real-world scenario.

Graph Theoretical Analysis on Distributed Line Graphs for Peer-to-Peer Networks

Distributed line graphs were introduced by Zhang and Liu as an overlay for Peer-to-Peer networks. Distributed line graphs have some useful properties as a network topology, such as out-regular and small diameter, where the former implies that each user possesses a constant size of routing table and the latter means that a reasonably small number of hops is necessary to reach a target user. In this paper, we newly introduce distributed line sharp graphs, as an extension of distributed line graphs, so as to further expand the possibility of finding better network topologies and theoretically analyze their properties. The analysis on the distributed line sharp graphs is based on the analysis on distributed line graphs presented by Zhang and Liu. In particular, we further examine the diameter and the in-degree of a vertex, and improve the previous results together with detailed proofs. We also show that the diameter of a certain distributed line sharp graph is equal to the diameter of its corresponding distributed line graph.

Selection of High Quality Path through MXAODV in Mobile Ad-Hoc Network

Selection of high quality path in mobile ad-hoc network is a critical issue due to mobility of nodes and variable channel conditions during data transmission. Path containing smallest number of hops generally performs less due to some links on those paths may have low or marginal quality. Mean loss ratio of link is also not a perfect way to estimate link quality, mean channel condition is not realistic. Hence, link quality estimation on the basis of loss ratio in burst loss conditions of different channels is significant. Incorporation of loss variance for a link in its quality estimation through modified expected transmission count (mETX) is the main aim of the proposed protocol to improve the communication efficiency in mobile ad-hoc networks. This paper describes the design and implementation of proposed routing protocol named as modified expected transmission count enabled ad-hoc on-demand distance vector (MXAODV). Extensive simulation has been done to analyse the performance of MXADOV. Significant improvements found in terms of throughput, packet delivery fraction, normalised routing load and end-to-end delay.

Estimating Infection Sources in Networks Using Partial Timestamps

We study the problem of identifying infection sources in a network based on the network topology, and a subset of infection timestamps. In the case of a single infection source in a tree network, we derive the maximum likelihood estimator of the source and the unknown diffusion parameters. We then introduce a new heuristic involving an optimization over a parametrized family of Gromov matrices to develop a single source estimation algorithm for general graphs. Compared with the breadth-first search tree heuristic commonly adopted in the literature, simulations demonstrate that our approach achieves better estimation accuracy than several other benchmark algorithms, even though these require more information like the diffusion parameters. We next develop a multiple sources estimation algorithm for general graphs, which first partitions the graph into source candidate clusters, and then applies our single source estimation algorithm to each cluster. We show that if the graph is a tree, then each source candidate cluster contains at least one source. Simulations using synthetic and real networks, and experiments using real-world data suggest that our proposed algorithms are able to estimate the true infection source(s) to within a small number of hops with a small portion of the infection timestamps being observed.

Efficient influence spread estimation for influence maximization under the linear threshold model

This paper investigates the influence maximization (IM) problem in social networks under the linear threshold (LT) model. Kempe et al. (ACM SIGKDD Conference on Knowledge Discovery and Data Mining, pp. 137–146, 2003) showed that the standard greedy algorithm, which selects the node with the maximum marginal gain repeatedly, brings a -factor approximation solution to this problem. However, Chen et al. (International Conference on Data Mining, pp. 88–97, 2010) proved that the problem of computing the expected influence spread (EIS) of a node is #P-hard. Therefore, to compute the marginal gain exactly is computational intractable. We step-up on investigating efficient algorithm to compute EIS. We show that the EIS of a node can be computed by finding cycles through it, and we further develop an exact algorithm to compute EIS within a small number of hops and an approximation algorithm to estimate EIS without the hop constraint. Based on the proposed EIS algorithms, we finally develop an efficient greedy based algorithm for IM. We compare our algorithm with some well-known IM algorithms on four real-world social networks. The experimental results show that our algorithm is more accurate than others in finding the most influential nodes, and it is also better than or competitive with them in terms of running time. IM is a big topic in social network analysis. In this paper, we investigate efficient influence spread estimation for IM under the LT model. We develop two influence spread estimation algorithms and a new greedy based algorithm for IM under the LT model. The performance of the proposed algorithms are analyzed theoretically and evaluated through simulations.

An efficient MAC scheme for secure network coding with probabilistic detection

Network coding is vulnerable to pollution attacks, which prevent receivers from recovering the source message correctly. Most existing schemes against pollution attacks either bring significant redundancy to the original message or require a high computational complexity to verify received blocks. In this paper, we propose an efficient scheme against pollution attacks based on probabilistic key pre-distribution and homomorphic message authentication codes (MACs). In our scheme, each block is attached with a small number of MACs and each node can use these MACs to verify the integrity of the corresponding block with a high probability. Compared to previous schemes, our scheme still leverages a small number of keys to generate MACs for each block, but more than doubles the detection probability.Meanwhile, our scheme is able to efficiently restrict pollution propagation within a small number of hops. Experimental results show that our scheme is more efficient in verification than existing ones based on public-key cryptography.

On new measurement and communication techniques of GNSS inter-satellite links

This paper studies the key techniques of the measurement and communication system for inter-satellite links (ISLs) of global navigation satellite system. A fixed link topology is designed based on the analysis of inter-satellite geometric properties and spatial parameters of the standard Walker24/3/2 constellation. This design can achieve full network coverage with small number of hops, significantly reduce the number of ISLs, and enhance the feasibility and reliability of the system. A new time-division duplex mode, as well as an integrated measurement and communication scheme, is proposed based on the designed topology. Furthermore, mathematical formulas, error models, and modification methods regarding two-way ranging and time synchronization algorithms using spread spectrum non-coherent data frame for this new system are comprehensively discussed. Theoretical analysis and simulation studies demonstrate that our design, compared with current GPS systems, has higher ranging and time synchronization precision, improved measurement efficiency, and higher channel utilization ratio and data transmission rate. It has no restrictions of constellation configuration, making it suitable for both MEO and the future MEO/GEO hybrid constellations. The results in this paper can serve as strong technical support for the next generation of GNSS ISL.

Heuristic algorithms for effective broker deployment

In the pervasive e-business applications covering large geographical areas and involving many RFID readers or sensors, broker deployment strategies have a direct effect on the deployment cost and collaboration efficiency. By analyzing the deployment cost and collaboration basis, this paper proposes a model for the broker deployment problem, and presents two heuristic algorithms for the multi-object optimization of broker deployment, where one is for the deployment area which contains the zones forbidden to place brokers in, and the other is for the deployment area without any forbidden zone. Experiments are conducted to demonstrate the effectiveness of the proposed algorithms. The experimental results also show the deployment algorithms have the advantage of being low cost of deployment. Moreover, the brokers deployed carry relatively balanced loads and messages are forwarded from an event source to a broker over a small number of hops.

RAI: A High Throughput Routing Protocol for Multi-hop Multi-rate Ad hoc Networks

The advantages of using the multiple rates for wireless communications have been revealed in the recent years. To determine the appropriate rate and to make routing decision more precise, the communication nodes need the information from lower layer. Therefore, in this paper, a high throughput routing protocol using lower layer information for Multi-rate Ad-hoc Networks is proposed. We introduce a new routing metric named "Route Assessment Index" (RAI). The route with maximum RAI value is preferred to achieve the high throughput route, and to avoid the link bottleneck for reducing the packet drop rate. The chosen route also has a small number of hops. The routing protocol works in distributed manner, and correctness of the proposal is proven. The simulation results show that our new metric provides an accurate and efficient method for assessing and selecting the best route in Multi-rate Ad-hoc Networks.

DiffServ-based bandwidth-constrained anycast routing in a mobile IPv6 network

This paper proposes a differentiated service (DiffServ)-based bandwidth-constrained network layer anycast routing for a mobile IPv6 network. The proposed algorithm comprises three steps: (1) When moving into a new foreign network, the mobile node (MN) chooses a feasible path to easily locate the nearest server that can serve it. To perform path selection, a multi-level list structure (MLLS) is defined and used to store the available bandwidth and hop count of a path. (2) An ingress extended edge router (E-ER) uses the multi-level list algorithm (MLLA) to examine the MLLS for selecting the feasible path with the smallest number of hops that satisfies the MN bandwidth request. (3) The E-ER uses a condition of path change (CPC) variable to determine whether it should optimize the route between itself and the server. Simulation results indicate that the proposed algorithm offers better performance than the existing related approaches in terms of the average running time, request blocking rate, and reducing the control overhead of the simulated network. Copyright © 2010 John Wiley & Sons, Ltd.

Design and analysis of a multi-candidate selection scheme for greedy routing in wireless sensor networks

Sleep and wake-up scheduling of sensor nodes is an efficient solution to prolong the network lifetime. However, existing scheduling algorithms may significantly decrease the number of active nodes so that the network may be intermittently connected. In such networks, traditional geographic routing protocols are inappropriate to obtain low latency routes due to route discovery and data forwarding latency. In this paper, we propose a novel multi-candidate selection (MCS) scheme for greedy routing that makes the best effort to find minimum latency routes in the sensor networks. In MCS, each source node sends an RREQ to a list of first wake-up forwarder candidates and selects a route with minimum estimated delivery latency based on their replies. The route found by MCS may be longer than that of distance-based greedy forwarding (DGF) ( Finn, 1987). Hence, we introduce a latency-adaptive distance-based multi-candidate selection scheme for greedy forwarding to find routes with a small number of hops and acceptable delivery latency. Probabilistic analysis and simulation results demonstrate that MCS increases the routing performance significantly compared with DGF and ODML ( Su et al., 2008) in terms of delivery latency.

The effects of the number of neighbors in multihop wireless networks

PurposeIn multihop wireless networks, the number of neighbors has an important role in the network performance since links are dynamically formed between a node and its neighbors. This paper aims to investigate this issue.Design/methodology/approachThe paper quantitatively studies the effects of the average number of neighbors in multihop wireless networks on the network connectivity, the number of hops needed to traverse a certain distance, which can be used to determine the hop diameter of a network, and the total energy consumed by packet transmission, which can be used to choose an optimum average number of neighbors that minimizes the energy consumption. This paper also presents an analysis of the energy consumption that can be applied to a wide range of access protocols and show the effect of a variety of factors.FindingsResults show that the minimum average number of neighbors to guarantee the overall network connectivity depends on the size of a network coverage. There is a sharp knee in the network connectivity with decrease of the average number of neighbors, N. If the distance between a source and destination, d, is known, the number of hops needed to reach the destination is usually between d/R∼2d/R, where R is the transmission range. A larger average number of neighbors N leads to a smaller number of hops to traverse a certain distance, which in turn results in a smaller traffic load caused by relaying packets. However, a bigger N also causes more collisions when a contention medium access scheme is used, which leads to more energy consumed by packet transmission. The results show that the optimum N which minimizes the energy is obtained by balancing several factors affecting the energy.Originality/valueThe paper provides a useful study on the effects of the number of neighbors in multihop wireless networks.

Full-Information Lookups for Peer-to-Peer Overlays

Most peer-to-peer lookup schemes keep a small amount of routing state per node, typically logarithmic in the number of overlay nodes. This design assumes that routing information at each member node must be kept small so that the bookkeeping required to respond to system membership changes is also small, given that aggressive membership dynamics are expected. As a consequence, lookups have high latency as each lookup requires contacting several nodes in sequence. In this paper, we question these assumptions by presenting a peer-to-peer routing algorithm with small lookup paths. Our algorithm, called ldquoOneHop,rdquo maintains full information about the system membership at each node, routing in a single hop whenever that information is up to date and in a small number of hops otherwise. We show how to disseminate information about membership changes quickly enough so that nodes maintain accurate complete membership information. We also present analytic bandwidth requirements for our scheme that demonstrate that it could be deployed in systems with hundreds of thousands of nodes and high churn. We validate our analytic model using a simulated environment and a real implementation. Our results confirm that OneHop is able to achieve high efficiency, usually reaching the correct node directly 99 percent of the time.

An ant colony optimization routing based on robustness for ad hoc networks with GPSs

Ant colony optimization (ACO) routing algorithm is one of adaptive and efficient routing algorithms for mobile ad hoc networks (MANETs). In ACO routing algorithms, ant-like agents traverse the network to search a path from a source to a destination, and lay down pheromone on the path. A data packet is transferred along a path selected with probability based on the amount of pheromone. The amount of pheromone laid down on a path depends on its quality, such as its number of hops and communication delay. However, in MANETs, continuous movement of nodes causes dynamic network change with time. Thus, even if a path with a small number of hops and short communication delay has much pheromone, it may become unavailable quickly due to link disconnections. Therefore, we focus on robustness of paths to construct paths that are not likely to be disconnected during a long period. In this paper, we propose a new ACO routing algorithm based on robustness of paths for MANETs with global positioning system (GPS): each ant-like agent evaluates robustness of a path using GPS information of visited nodes and decides the amount of pheromone to lay down based on the robustness. Moreover, in our algorithm, each node predicts link disconnections from neighbors’ GPS information in order to adapt to dynamic network change. To keep paths available, when a node predicts a link disconnection, it redistributes the pheromone on the link to be disconnected so that construction of alternative paths can be accelerated. Simulation results show that our algorithm achieves higher packet delivery ratio with lower communication cost than AntHocNet and LAR.