Large Network Capacity Research Articles

Research on multi-address autonomous access technology of uav cluster data link based on priority statistics

As a uav cluster that can change the future combat situation, its data link has the requirements of high speed, low delay, dynamic networking and large network capacity. In this paper, a priority statistics based multi-address autonomous access technology for uav cluster data link is studied. Firstly, the channel load is detected and predicted by time-frequency analysis for different priority services. Then, multi-node information fusion is adopted for multi-address decision-making. Finally, the designed technology is simulated by Qualnet software. The simulation results show that the proposed multi-address autonomous access technology based on priority statistics can effectively reduce in-network channel collisions and realize low-delay transmission of high-priority services.

Multipath transport and packet spraying for efficient data delivery in data centres

Modern data centres provide large aggregate network capacity and multiple paths among servers. Traffic in data centres is very diverse; most of the data is produced by long, bandwidth hungry flows but the large majority of flows, which commonly come with stringent deadlines regarding their completion time, are short. It has been shown that TCP is not efficient for any of these types of traffic in modern data centres. MultiPath TCP (MPTCP) employs multipath data transport and is efficient for long flows but ill-suited for short flows.In this paper, we present Maximum MultiPath TCP (MMPTCP), a novel transport protocol which extends MPTCP and, compared to TCP and MPTCP, reduces short flows’ completion times, while providing excellent goodput to long flows. To do so, MMPTCP runs in two phases; initially, it randomly scatters packets in the network under a single congestion window exploiting all available paths. This is beneficial to latency-sensitive flows. After a specific amount of data is sent, MMPTCP switches to a regular MultiPath TCP mode. MMPTCP is incrementally deployable in existing data centres as it does not require any modifications outside the transport layer and behaves well when competing with MPTCP flows. We also present a topology-specific extension of MMPTCP that adjusts the numbers of subflows during the second phase of the protocol based on knowledge about the location of the receiver in the data centre.We present extensive evaluation that shows that MMPTCP’s design objectives are met. We have implemented MMPTCP (along with MPTCP and packet spraying) in ns-3 and evaluated our protocol in simulated FatTree topologies. We have evaluated how MMPTCP performs compared to TCP and MPTCP and how its performance is affected by transient hotspots in the network. We have also experimented with different thresholds for duplicate acknowledgements and fast retransmissions and shown that MMPTCP performs well when the size of short flows is widely ranged. Finally, we have evaluated how MMPTCP performs under conditions that result in Incast, when different congestion control algorithms are used in its second phase and when varying the overall network load.

Toward Optimal Remote Radio Head Activation, User Association, and Power Allocation in C-RANs Using Benders Decomposition and ADMM

To satisfy the rapidly growing demands of wireless communications, new structures have been proposed for the fifth-generation (5G) mobile communication networks, such as cloud radio access networks (C-RANs), which have advantages including high energy efficiency, large network capacity, and high flexibility. This paper concentrates on the problem of remote radio head (RRH) activation, user association, and power allocation in C-RANs. To tackle the problem with $l_{0}$ norm, we transform it into a mixed-integer nonlinear programming (MINLP) problem. Instead of solving it by centralized solvers, we propose a novel algorithm based on Benders decomposition, which can obtain the optimal solution of the MINLP problem. To solve the primal problem in Benders decomposition efficiently, we adopt the alternating direction method of multipliers (ADMM) to achieve a parallel implementation. To further reduce the complexity of solving the MINLP problem, a distributed two-stage iterative algorithm combining the ADMM and the max-sum algorithm is also proposed. The simulation results demonstrate that the first proposed algorithm can obtain the optimal solution, and the second proposed algorithm outperforms conventional algorithms significantly.

A Distance-Vector-Based Multi-Path Routing Scheme for Static-Node-Assisted Vehicular Networks.

Vehicular Ad hoc NETworks (VANET) has been well studied for a long time as a means to exchange information among moving vehicles. As vehicular networks do not always have connected paths, vehicular networks can be regarded as a kind of delay-tolerant networks (DTNs) when the density of vehicles is not high enough. In this case, packet delivery ratio degrades significantly so that reliability of networks as an information infrastructure is hardly held. Past studies such as SADV (Static-node Assisted Data dissemination protocol for Vehicular networks) and RDV (Reliable Distance-Vector routing) showed that the assistance of low-cost unwired static nodes located at intersections, which work as routers to provide distance-vector or link-state routing functions, significantly improves the communication performance. However, they still have problems: SADV does not provide high-enough delivery ratio and RDV suffers from traffic concentration on the shortest paths. In this paper, we propose MP-RDV (Multi-Path RDV) by extending RDV with multiple paths utilization to improve performance against both of those problems. In addition, we apply a delay routing metric, which is one of the major metrics in this field, to RDV to compare performance with the traffic-volume metric, which is a built-in metric of RDV. Evaluation results show that MP-RDV achieves high load-balancing performance, larger network capacity, lower delivery delay, and higher fault tolerance against topology changes compared to RDV. As for routing metrics, we showed that the traffic-volume metric is better than the delay one in RDV because delay measurement is less stable against traffic fluctuation.

Modeling a Novel Network Coding Aware Routing Protocol for Enhancement of Network Performance in Wireless Mesh Network

A Wireless Mesh Network (WMN) is a multi-hop network that gains the benefits of low deployment cost, fast access speed, expanded service coverage and large network capacity. However, the multi-hop communication in WMNs limits the throughput capacity due to increased number of packet transmissions. As a result, network coding is a recently emerged paradigm that can enhance the throughput capacity (i.e. network throughput) by minimizing the quantity of network workload and at the same time it ensures the data transfer among all the users. Further, with network coding the transmission effectiveness of a node can be improved by encoding (combining) several packets collectively and verifies whether the coding strategies is satisfied or not. Subsequently, if the coding strategies are satisfied then it transmits only the resultant encoded packet to the desired destination. In other words, network coding can improve the network throughput in WMNs by minimizing the transmission counts needed to transfer several packets to the destination. It should be noted that, while employing network coding in WMNs there are several challenges that should be compensated such as (i) identifying packets that can be combined (encoded) collectively and (ii) integrating the coding strategies in routing protocols. In this paper, we proposed a new mesh routing protocol that integrates network-coding called as Network Coding Aware Routing (Net-CART) protocol. Therefore, to enjoy the whole benefit of network coding a Net-CART protocol uses the innovative routing metric called Code-Aware and Load-Aware Routing Metric. Additionally, to identify numerous ‘coding structures’ and to support number of ‘packet encodings’ an improved set of coding strategies known as Enhanced Universal Coding Strategies is also proposed. The proposed Net-CART protocol comprising an improved set of coding strategies and a new routing-metric considers both the coding-opportunities and “network workload”. The simulation study carried out in wide forms of network configurations showed that Net-CART gives more fairness performances than other protocols.

Relay Assisted Concurrent Scheduling to Overcome Blockage in Full-Duplex Millimeter Wave Small Cells

The millimeter wave (mmWave) has been extensively utilized for its rich spectrum resource. With the development of self-interference (SI) cancellation technology, full-duplex (FD) communications have become possible recently. In order to get larger network capacity, we introduce FD communications into mmWave wireless network. However, mmWave links are easily blocked by obstacles, and the blockage makes some flows fail to be transmitted directly. For the communication problems of shadow coverage area, a relay path selection algorithm is proposed to select optimal multi-hop paths for these blocked flows. This proposed algorithm not only can relay the blocked flows by other unblocked links, but also select the appropriate relay paths to minimize transmission time of the entire transmission process. To further improve the system transmission efficiency, we develop a concurrent scheduling algorithm by using FD communications. The scheduling algorithm continuously schedules the links until the throughput requirements of flows are accommodated. Through extensive simulations at 60 GHz mmWave wireless network, the proposed scheme can solve the problem for a certain degree of blocked flows and complete the transmission with the least time consumption. Compared with other existing schemes, the proposed scheme shows superior performances on relaying capability and scheduling duration.

Integrating Capacity and Logistics of Large Additive Manufacturing Networks

Among future manufacturing systems, we are going to see networks of intelligent and autonomous entities sharing manufacturing resources, knowledge and information. Possible advantages are relevant, such as increasing overall production efficiency and product variety as well as reducing responsiveness and lead times. This paper focuses on the architectures and dynamics of productive-demanding nodes in a Scattered Manufacturing (SM) Network, with an application in Additive Manufacturing scenarios. SM allows launching production orders everywhere anytime inside the domain of the network. These autonomous nodes can rely on on-demand manufacturing services by sharing resources in a geographically distributed network. One possible approach is the introduction of a platform to coordinate the dynamics along the network according to principles of sustainability, equated shared resources and transparency by managing communication activities among nodes. To identify variables/factors that affect the system, a unique model is proposed by combining different perspectives, which focus on: a) decomposition and localization of demanding node’s order into subtasks of variable size; b) tasks allocation criteria among geographically distributed nodes; c) logistics issues related to the localization of productive nodes. In particular, the model, with the aim of optimizing the overall manufacturing and logistics costs, suggests either logistics paths along the sub-network or tasks assignment criteria and scheduling in geographically distributed nodes.

DISH

The MAC standard amendment IEEE 802.15.4e is designed to meet the requirements of industrial and critical applications. In particular, the Time Slotted Channel Hopping (TSCH) mode divides time into periodic, equally sized, slotframes composed of transmission timeslots. Then, it combines time slotted access with multichannel and channel hopping capabilities, providing large network capacity, high reliability, and predictable latency while ensuring energy efficiency. Since every network node considers the same timeslots at each slotframe and selects physical channels according to a periodic function, TSCH produces a steady channel utilization pattern. This can be exploited by a selective jammer to entirely thwart communications of a victim node in a way that is stealthy, effective, and extremely energy efficient. This article shows how a selective jamming attack can be successfully performed even though TSCH uses the IEEE 802.15.4e security services. Furthermore, we propose DISH, a countermeasure which randomly permutes the timeslot and channel utilization patterns at every slotframe in a consistent and completely distributed way without requiring any additional message exchange. We have implemented DISH for the Contiki OS and tested its effectiveness on TelosB sensor nodes. Quantitative analysis for different network configurations shows that DISH effectively contrasts selective jamming with negligible performance penalty.

Surrogate Model-Based Energy-Efficient Scheduling for LPWA-Based Environmental Monitoring Systems

The rapid development of the Internet of Things (IoTs) with newly proposed wireless communication technology has compactly generated connections between humans and the physical world. Beginning with research on wireless sensor networks, environmental monitoring research has currently developed into wider applications aiming to detect the world with multitudinous IoT technologies. Recently, low power wide area technologies have provided such benefits as longer communication range, larger network capacity, and low unit-price, providing more choices for managers to set up more detailed monitoring. However, the operational lives of battery-powered end-devices still hinder long-term monitoring. In this paper, we propose a decentralized framework for energy-efficient environmental monitoring considering both the operation cost and current computational capabilities of the end-devices. The core function is a low-complexity scheduling approach that can balance the monitoring performance and energy consumption for different environmental states. Driven by the prediction accuracy of the surrogate model, monitoring nodes are selected. Meanwhile, the energy consumption of the other nodes is saved. Simulation results demonstrate that the proposed monitoring system has high energy efficiency with acceptable performance. The battery life of the whole system can be prolonged by up to 136.22%.

The Effects of Topology on Throughput Capacity of Large Scale Wireless Networks

In this paper, we jointly consider the inhomogeneity and spatial dimension in large scale wireless networks. We study the effects of topology on the throughput capacity. This problem is inherently difficult since it is complex to handle the interference caused by simultaneous transmission. To solve this problem, we, according to the inhomogeneity of topology, divide the transmission into intra-cluster transmission and inter-cluster transmission. For the intra-cluster transmission, a spheroidal percolation model is constructed. The spheroidal percolation model guarantees a constant rate when a power control strategy is adopted. We also propose a cube percolation mode for the inter-cluster transmission. Different from the spheroidal percolation model, a constant transmission rate can be achieved without power control. For both transmissions, we propose a routing scheme with five phases. By comparing the achievable rate of each phase, we get the rate bottleneck, which is the throughput capacity of the network.

Joint flow routing-scheduling for energy efficient software defined data center networks: A prototype of energy-aware network management platform

Data centers are a cost-effective infrastructure for hosting Cloud and Grid applications, but they do incur tremendous energy cost and CO2 emissions. Today׳s data center network architectures such as Fat-tree and BCube are over-provisioned to guarantee large network capacity and meet peak performance requirement. Networks suffer from inefficient power usage when data center traffic is not high. A solution to this problem is the adoption of network management platform such as OpenNaaS, which can be augmented with energy-aware capabilities. We developed a component for energy monitoring and routing in OpenNaaS. Energy-aware OpenNaaS can support different types of OpenFlow controller; it inherits and enhances network management capabilities, e.g. dynamically obtaining power and topology.In this paper we also discuss the evaluation and selection of energy-aware routing strategies based on an initial prototype of energy-aware OpenNaaS. The target strategies are fine-grained as they combine flow routing algorithms that make routing decisions for the flows and flow scheduling algorithms that schedule the flows on the same link. Differently from previous routing work which focuses on power-minimization problem in data center networks, we aim to optimize energy consumption. Our simulation shows that the combination of priority-based shortest routing and exclusive flow scheduling achieves about 5%–35% higher energy efficiency without performance degradation.

A Truthful Double Auction for Device-to-Device Communications in Cellular Networks

Data traffic in cellular networks has dramatically increased in recent years as the emergence of various new wireless applications, which imposes an immediate requirement for large network capacity. Although many efforts have been made to enhance wireless channel capacity, they are far from solving the network capacity enhancement problem. Device-to-Device (D2D) communication is recently proposed as a promising technique to increase network capacity. However, most existing work on D2D communications focuses on optimizing throughput or energy efficiency, without considering economic issues. In this paper, we propose a truthful double auction for D2D communications (TAD) in multi-cell cellular networks for trading resources in frequency-time domain, where cellular users with D2D communication capability act as sellers, and other users waiting to access the network act as buyers. Both intra-cell and inter-cell D2D sellers are accommodated in TAD while the competitive space in each cell is extensively exploited to achieve a high auction efficiency. With a sophisticated seller-buyer matching, winner determination and pricing, TAD guarantees individual rationality, budget balance, and truthfulness. Furthermore, we extend our TAD design to handle a more general case that each seller and buyer ask/bid multiple resource units. Extensive simulation results show that TAD can achieve truthfulness as well as high performance in terms of seller/buyer sanctification ratio, auctioneer profit and network throughput.

Training in the Conduct of Population-Based Multi-Site and Multi-Disciplinary Studies: the Cancer Research Network's Scholars Program.

Expanding research capacity of large research networks within health care delivery systems requires strategically training both embedded and external investigators in necessary skills for this purpose. Researchers new to these settings frequently lack the skills and specialized knowledge conducive to multi-site and multi-disciplinary research set in delivery systems. This report describes the goals and components of the Cancer Research Network (CRN) Scholars Program, a 26-month training program developed to increase the capacity for cancer research conducted within the network's participating sites, its progression from training embedded investigators to a mix of internal and external investigators, and the content evolution of the training program. The CRN Scholars program was launched in 2007 to assist junior investigators from member sites develop independent and sustainable research programs within the CRN. Resulting from CRN's increased emphasis on promoting external collaborations, the 2013 Scholars program began recruiting junior investigators from external institutions committed to conducting delivery system science. Based on involvement of this broader population and feedback from prior Scholar cohorts, the program has honed its focus on specific opportunities and issues encountered in conducting cancer research within health care delivery systems. Efficiency and effectiveness of working within networks is accelerated by strategic and mentored navigation of these networks. Investing in training programs specific to these settings provides the opportunity to improve multi-disciplinary and multi-institutional collaboration, particularly for early-stage investigators. Aspects of the CRN Scholars Program may help inform others considering developing similar programs to expand delivery system research or within large, multi-disciplinary research networks.

Capacity of large hybrid erasure networks with random node distribution

The Gupta---Kumar's nearest-neighbor multihop routing with/without infrastructure support achieves the optimal capacity scaling in a large erasure network in which n wireless nodes and m relay stations are regularly placed. In this paper, a capacity scaling law is completely characterized for an infrastructure-supported erasure network where n wireless nodes are randomly distributed, which is a more feasible scenario. We use two fundamental path-loss attenuation models (i.e., exponential and polynomial power-laws) to suitably model an erasure probability. To show our achievability result, the multihop routing via percolation highway is used and the corresponding lower bounds on the total capacity scaling are derived. Cut-set upper bounds on the capacity scaling are also derived. Our result indicates that, under the random erasure network model with infrastructure support, the achievable scheme based on the percolation highway routing is order-optimal within a polylogarithmic factor of n for all values of m.

Massive MIMO Performance Evaluation Based on Measured Propagation Data

Massive MIMO, also known as very-large MIMO or large-scale antenna systems, is a new technique that potentially can offer large network capacities in multi-user scenarios. With a massive MIMO system, we consider the case where a base station equipped with a large number of antenna elements simultaneously serves multiple single-antenna users in the same time-frequency resource. So far, investigations are mostly based on theoretical channels with independent and identically distributed (i.i.d.) complex Gaussian coefficients, i.e., i.i.d. Rayleigh channels. Here, we investigate how massive MIMO performs in channels measured in real propagation environments. Channel measurements were performed at 2.6 GHz using a virtual uniform linear array (ULA) which has a physically large aperture, and a practical uniform cylindrical array (UCA) which is more compact in size, both having 128 antenna ports. Based on measurement data, we illustrate channel behavior of massive MIMO in three representative propagation conditions, and evaluate the corresponding performance. The investigation shows that the measured channels, for both array types, allow us to achieve performance close to that in i.i.d. Rayleigh channels. It is concluded that in real propagation environments we have characteristics that can allow for efficient use of massive MIMO, i.e., the theoretical advantages of this new technology can also be harvested in real channels.

Transport Capacity of Distributed Wireless CSMA Networks

In this paper, we study the transport capacity of large multi-hop wireless CSMA networks. Different from previous studies which rely on the use of centralized scheduling algorithm and/or centralized routing algorithm to achieve the optimal capacity scaling law, we show that the optimal capacity scaling law can be achieved using entirely distributed routing and scheduling algorithms. Specifically, we consider a network with nodes Poissonly distributed with unit intensity on a $\sqrt{n}\times\sqrt{n}$ square $B_{n}\subset\Re^{2}$. Furthermore, each node chooses its destination randomly and independently and transmits following a CSMA protocol. By resorting to the percolation theory and by carefully tuning the three controllable parameters in CSMA protocols, i.e. transmission power, carrier-sensing threshold and count-down timer, we show that a throughput of $\Theta\left(\frac{1}{\sqrt{n}}\right)$ is achievable in distributed CSMA networks. Furthermore, we derive the pre-constant preceding the order of the transport capacity by giving an upper and a lower bound of the transport capacity. The tightness of the bounds is validated using simulations.

Transmission Line Status Monitoring System Based on Ad Hoc Network

Based on the basic principle of wireless sensor networks, the communication platform of a new ZigBee wireless ad hoc network is applied to the on-line monitoring system of transmission lines. In this article, the hardware and software platform architecture of the system is introduced, the scheme and algorithm for cluster network of monitoring nodes based on ZigBee technology are described; moreover a reliable, energy-saving and efficient data transmission method is designed. Application results show that ZigBee technology has the features such as self-organization, dynamic topology, large network capacity and data-centeredness, and possess a distinct advantage in on-line monitoring of electrical equipments.

Capacity of Large Wireless Networks with Generally Distributed Nodes

This paper investigates the capacity of a random network in which the nodes have a general spatial distribution. Our model assumes n nodes in a unit square, with a pair of nodes directly connected if and only if their Euclidean distance is smaller than or equal to a threshold, known as the transmission range. Each link has an identical capacity of W bits/s. The transmission range is the same for all nodes and can be any value so long as the resulting network is connected. A capacity upper bound is obtained for the above network, which is valid for both finite n and asymptotically infinite n. We further investigate the capacity upper bound and lower bound for the above network as n → ∞ and show that both bounds can be expressed as a product of four factors, which represents respectively the impact of node distribution, link capacity, number of source destination pairs and the transmission range. The bounds are tight in that the upper bound and lower bound differ by a constant multiplicative factor only. For the special case of networks with nodes distributed uniformly or following a homogeneous Poisson distribution, the bounds are of the same order as known results in the literature.

Impact of Multidirectional Forwarding on the Capacity of Large Wireless Networks

We consider the capacity problem in large wireless multihop networks by separating the problem into macroscopic and microscopic level subproblems. At the macroscopic level, the task is to determine the routes that are geometric curves. At the microscopic level, we need to forward the traffic according to its directional distribution that results from the macroscopic level routes. Previous studies have treated the macroscopic level problem simply as that of load balancing, implying the use of time sharing to serve the traffic flowing in different directions. We study how a scheduling that truly interleaves the traffic flows in different directions affects the macroscopic level problem. We restrict the macroscopic routes to certain simple path sets. This together with earlier results on the microscopic level forwarding capacity allows us to obtain new results on the macroscopic level capacity that demonstrate the gains from multidirectional forwarding.

Design of the Wireless Data Acquisition System – Substation Management System

Aiming at the problems of the poor extensibility, complicated routing and inconvenient for real-time monitoring of the traditional data acquisition of the Overhead Crane, the wireless data acquisition system was designed based on the industrial wireless transmission equipment. This system takes the use of ND250 digital radio, the Schenck weighting sensor and the industrial control computer. Combining with the weighting data management software in the upper system, the wireless data acquisition system of the Overhead Crane has been realized in this paper. Compared with the traditional data acquisition system, this system own the superiority of low power consumption, large network capacity and flexible organized-manners .