Network Capacity Research Papers - Academia.edu (original) (raw)

Key Words -Positive and complementary indexes, Mean normalized capacity, Pseudo-switching function, Map method, Reduction rule, Generalized Max-Flow Min-Cut Theorem Rcodrr Aids -Purpose: Tutorial Special math needed for explanations: Probability Special math needed to use results: Same Results useful to: Reliability and telecommunication analysts Abstract -Two recently proposed performance indexes for telecommunication networks are shown to be the s-t and overall versions of the same measure, vlz, the mean normalized network capacity. The network capacity is a pseudo-switching function of the branch successes, and hence its mean value is readily obtainable from its sum-of-products expression. Three manual techniques of conventional reliability analysis are adapted for the computation of the new performance indexes, viz, a map procedure, reduction rules, and a generalized cutset procedure. Four tutorial examples illustrate these techniques and demonstrate their computational advantages over the stateenumeration technique.

- by
- •
- Computer Networks, Stress, Reliability Theory, Stochastic processes

The hardest problem facing sensor networking today is the design and implementation of complex routing structures and application semantics for collaborative in-network processing on motes. Researchers have not been able to develop... more

- by Marcos Vieira
- •
- Sensor Network, Network Capacity, University of Southern California, Large Scale

We present a model of energy consumption in IP networks. Using this model, we identify energy ldquohotspotsrdquo and estimate how energy consumption will grow with increasing network capacity. Todaypsilas Internet uses less than 1% of the available electricity supply. However, network energy consumption could grow substantially as access rates increase.

- by Kerry Hinton
- •
- Optics, Medical Imaging, Fiber Optics, Telecommunications
- by Ralf Herber
- •
- Spine, Modeling, Broadband Networks, Cost effectiveness

This article proposes a method that can calculate the blocking probability of multi-service cellular systems with Wideband Code Division Multiple Access radio interface. The method considers a finite and an infinite source population and takes into account the interdependency of calls service processes in neighboring cells and in both the uplink and the downlink directions. The basis of the proposed method is the fixedpoint methodology. A comparison of the results of analytical calculations to those of simulations confirms the accuracy of the proposed method. The proposed scheme can realize cost-effective radio resource management in 3G mobile networks and can be easily applied to network capacity calculations.

- by Mariusz Glabowski (Głąbowski)
- •
- Computer Science, Radio Resource Management, Simulation, UMTS

From the network operator's point of view, the high CAPEX/OPEX cost resulting from fixed/wired backhaul links can be inhibitive to successful deployment of broadband wireless services. The emerging wireless mesh network (WMN) technology is seen as one of the potential solutions which may reduce wired backhaul dependency through multihop transmission. Despite the advantages, many remain sceptical on WMN's network capacity and scalability performances particularly when the user density is high. This paper provides an insight on the best possible upper-bound capacity performance of WMN, taking into consideration three key design parameters namely 1) Percentage of wired backhaul points per network, 2) Mesh-to-Access Link-Rate Ratio (R) and 3) Number of radio interfaces per mesh node including hybrid radio options. These design options are compared and contrasted with different deployment densities. The results generally show that the higher the number of backhaul points, the higher the effective access capacity available to mesh node and hence user domain. Increasing the R and the number of radio per mesh node are two alternative means to push up the effective access capacity per mesh node without increasing the number of wired backhaul points. This is most significant in multi radio system where about 80% of the backhaul points can be eliminated with R= 3 in order to maintain effective access capacity close to full rate (Capacity, C=1) per mesh node. It is also found that 50% of the backhaul points can be eliminated with R=2 for all radio options (except for the pure single radio case).

In this paper, we present a Minimum Spanning Tree (MST) based topology control algorithm, called Local Minimum Spanning Tree (LMST), for wireless multi-hop networks. In this algorithm, each node builds its local minimum spanning tree independently and only keeps on-tree nodes that are one-hop away as its neighbors in the final topology. We analytically prove several important properties of LMST: (1) the topology derived under LMST preserves the network connectivity; (2) the node degree of any node in the resulting topology is bounded by 6; and (3) the topology can be transformed into one with bi-directional links (without impairing the network connectivity) after removal of all uni-directional links. These results are corroborated in the simulation study.

- by abhishek tayal
- •
- Distributed Computing, Graph Theory, Energy Consumption, Topology Control

Measuring network path capacity is an important capability to many Internet applications. But despite over ten years of effort, the capacity measurement problem is far from being completely solved. This paper addresses the problem of measuring network paths of asymmetric capacity without requiring the remote node’s control or overwhelming the bottleneck link. We first show through analysis and measurement that the current packet-dispersion methods, due to the packet size limitations, can only measure up to a certain degree of capacity asymmetry. Second, we propose TRIO that removes the limitation by using round-trip times (RTTs). TRIO cleverly exploits two types of probes to obtain three minimum RTTs to compute both forward and reverse capacities, and another minimum RTT for measurement validation. We validate TRIO’s accuracy and versatility on a testbed and the Internet, and develop a system to measure path capacity from the server or user side.

- by Ricky K. P. Mok
- •
- Networking, Network Monitoring and Measurements, Network Capacity

The 802.11 MAC protocol is widely used in wireless mesh networks. However, with multi-hop transmissions prevalent in such networks, neither the current 802.11 DCF basic scheme nor the RTS/CTS scheme can achieve full utilization of network capacity for various reasons. First, the 802.11 MAC provides low spatial reuse (low parallelism of transmissions). Second, the collision avoidance mechanism in 802.11 becomes less effective for multi-hop scenarios. In this article, we review two types of 802.11-based MAC enhancements to improve the efficiency and effectiveness in wireless mesh networks. One class of schemes focus on tuning transmission power and carrier sense threshold. In static strategies, the interference model is introduced and a static optimal strategy is derived for the worst case scenarios. In dynamic strategies, transmission power and carrier sensing threshold are tuned adaptively to various network conditions and access patterns. Another class of schemes exploit the channe...

- by jian ZHANG
- •
- Collision Avoidance, Network Capacity, MAC Protocol

Two schools of thought exist in terms of handling mobility in mobile ad hoc networks (MANETs).

- by Shuhui Yang
- •
- Distributed Computing, Mobile Ad Hoc Networks, Routing, Synchronization

This paper describes a dynamic (multi-period) optimization model that has recently been used in Portugal to formulate planning proposals for the evolution of several school networks. This eort follows the extension of elementary education from 6 to 9 years as decided by the Government in 1986, and gradually implemented since then. The model allows for facility closure or size reduction, as well as facility opening and size expansion, with sizes limited to a set of pre-de®ned standards. It assumes facility costs are divided into a ®xed component and two variable components, dependent, respectively, on capacity and attendance. #

- by Samik Ghosh
- •
- Distributed Computing, Wireless Mesh Networks, Mobile Communication, Mesh Networks

This paper is an introduction to survivability of WDM networks. All the main optical protection techniques proposed as far as now for the WDM layer are classified and reviewed. In particular, commonly adopted protection strategies for ring and mesh networks are explained. Moreover, off-line planning of WDM networks able to support path protection is briefly introduced. Finally, an example of heuristic network-capacity optimization is presented, discussing results obtained by considering a case-study network.

- by mario martinelli
- •
- Case Study, Network Capacity, Optical network, MESH NETWORK

Wireless mesh networks (WMNs) consist of mesh routers and mesh clients, where mesh routers have minimal mobility and form the backbone of WMNs. They provide network access for both mesh and conventional clients. The integration of WMNs with other networks such as the Internet, cellular, IEEE 802.11, IEEE 802.15, IEEE 802.16, sensor networks, etc., can be accomplished through the gateway and bridging functions in the mesh routers. Mesh clients can be either stationary or mobile, and can form a client mesh network among themselves and with mesh routers. WMNs are anticipated to resolve the limitations and to significantly improve the performance of ad hoc networks, wireless local area networks (WLANs), wireless personal area networks (WPANs), and wireless metropolitan area networks (WMANs). They are undergoing rapid progress and inspiring numerous deployments. WMNs will deliver wireless services for a large variety of applications in personal, local, campus, and metropolitan areas. Despite recent advances in wireless mesh networking, many research challenges remain in all protocol layers. This paper presents a detailed study on recent advances and open research issues in WMNs. System architectures and applications of WMNs are described, followed by discussing the critical factors influencing protocol design. Theoretical network capacity and the state-of-the-art protocols for WMNs are explored with an objective to point out a number of open research issues. Finally, testbeds, industrial practice, and current standard activities related to WMNs are highlighted.

- by Simon Matabva
- •
- Engineering, Technology, Remote Sensing, Computer Networks

With wireless technologies extending to every part of our daily lives, mobile networking applications are becoming increasingly popular for accessing the Internet. Among them, web surfing is one of the most important applications because the World Wide Web has accelerated the dissemination of information and knowledge via the Internet unencumbered by geographic boundaries. In this paper, we propose a peer-to-peer approach, called PPWeb, for mobile web surfing. Unlike traditional approaches, the proposed scheme implements a Collaborative Forwarding algorithm that takes advantage of opportunistic wireless connections, thereby improving network capacity by exploiting the diversity of network mobility. Using simulations as well as real-world network scenarios, we demonstrate that the proposed scheme provides a better web surfing service than traditional schemes, and thus facilitates more effective web surfing on the go.

- by Ting-kai Huang
- •
- Wireless Technology, World Wide Web, Mobile Web, Network Capacity

Mobile communication networks alone consume 0.5 percent of the global energy today. Rapidly growing demand for capacity will further increase the energy consumption. Thus, improving energy efficiency has recently gained great interest within the research community not only for environmental awareness but also to lower the operational cost of network operators. Base station deployment strategy is one of the key challenges to be addressed for fulfilling the future capacity demand in an energy efficient manner. In this paper, we investigate the relationship between energy efficiency and densification with regard to network capacity requirement. To this end, we
refine the base station power consumption model such that the parameters are determined by the maximum transmit power and develop a simple analytical framework to derive the optimum transmit power that maximizes energy efficiency for a certain capacity target. Our framework takes into account interference, noise and backhaul power consumption. Numerical results show that deployment of smaller cells significantly reduces the base
station transmit power, and thus shifts the key elements of energy consumption to idling and backhauling power. Network densification can only be justified when capacity expansion is anticipated.

- by Sibel Tombaz and +1
- •
- Energy efficiency, Wireless Backhaul, Power Consumption, Network Capacity

Wireless Local Area Networks (WLANs) is one of the most promising access technologies for the upcoming fourth-generation wireless communication systems. In the last few years, several research efforts have been devoted to investigate possible multiple access schemes capable of supporting real-time traffic as well as best-effort data transmissions. In particular, the use of suitable transmission schemes allows not only to achieve higher data-rates, but also to perform resource allocation in order to guarantee specific service requirements. In this paper we propose a medium access control (MAC) scheme for a WLAN supporting realtime (voice) and best-effort (data) services, based on Orthogonal Frequency Division Multiplexing (OFDM) technique. A suitable analytical approach is proposed in order to derive the performance of the proposed MAC scheme. In particular, it is shown in the paper that a high overall network capacity in terms of simultaneously active users is achieved by effectively exploiting the multiuser capabilities offered by OFDM, together with a proper service differentiation.

The present paper considers a WDM optical packet ring in which multiple wavelengths are operated in a synchronous manner. This architecture attempts to blend packet switching techniques with optical transparency in order to offer a flexible MAN architecture able to accommodate large amounts of traffic demands. This architecture also performs traffic ldquogroomingrdquo (aggregation between different flows) but does not necessitate Optical-Electrical-Optical conversion in transit nodes. In each time slot, a ...

- by Philippe Gravey
- •
- Power Consumption, Network Capacity, Traffic Grooming, Network Dimensioning

Recently, several multi-channel MAC protocols have been proposed for wireless sensor networks (WSNs) to improve network capacity and boost energy efficiency. In addition, cooperative multiple-input multiple-output (MIMO) technique has been shown to be able to significantly enhance the energy efficiency of WSNs if properly configured. However, these two promising techniques have not been jointly utilized in WSNs. In this paper, we explore such a joint design by proposing a novel MAC protocol for WSNs that takes advantage of both multiple channels and cooperative MIMO. Specifically, sensor nodes in a WSN are organized into clusters and each cluster head selects some cooperative nodes to help forward traffic to or receive from other clusters by utilizing cooperative MIMO technique. For intra-cluster communications, different channels are assigned to adjacent clusters to reduce collisions, while for inter-cluster communications, cooperative MIMO links are scheduled to improve energy efficiency and concurrent transmissions are enabled by assigning different channels to them. We carry out extensive simulations and the results demonstrate that the proposed protocol can significantly increase throughput and improve energy efficiency compared to other schemes. For example, for a WSN with 150 nodes in a 250m × 250m field, with five or more available channels, the protocol can achieve over three times saturated throughput while saving up to 17% energy per bit for inter-cluster communications.

- by Sri vidhya J
- •
- Wireless Sensor Networks, Network Capacity, Wireless Sensor, Energy efficient

What is the capacity of the uplink of a radio network of receivers? We consider a spread spectrum model in which each user is decoded by all the receivers in the network (macrodiversity). We use a carrier-to-interference performance criterion that we derive from Shannon theory; each user must find the right transmitter power level to satisfy its carrier-tointerference constraint. Satisfying this requirement for all users is equivalent to solving a fixed point problem. We use this power control problem to derive the network capacity region and find that the feasibility of a configuration of users is independent of their positions in the network; each user can be assigned a bandwidth that is independent of the user's position in the network. Our capacity region is an upper bound over all schemes that treat the interference of other users as pure noise. To show that the capacity can be realized in practice, we propose a decentralized power adaptation algorithm and prove global convergence to the fixed point via a monotonicity argument.

- by Virgilio Rodriguez
- •
- Convergence, quantum Shannon theory, Fixed Point Theory, Spread Spectrum

Existing reliability studies of road networks are mainly limited to connectivity and travel time reliability and may not be sucient for a comprehensive network performance measure. Recently Chen et al. (J. Adv. Transp. 33 (2) (1999) 183±200) introduced capacity reliability as a new network performance index. It is de®ned as the probability that the network can accommodate a certain trac demand at a required service level, while accounting for drivers' route choice behavior. The proposed capacity reliability index includes connectivity reliability as a special case and also provides travel time reliability as a side product. This paper extends the capacity reliability analysis by providing a comprehensive methodology, which combines reliability and uncertainty analysis, network equilibrium models, sensitivity analysis of equilibrium network ow and expected performance measure, as well as Monte Carlo methods, to assess the performance of a degradable road network. Numerical results are also provided to demonstrate the feasibility of the proposed framework. Ó

- by k los
- •
- Applied Mathematics, Sensitivity Analysis, Reliability Analysis, Network Capacity
- by Miguel Castro
- •
- Machine Learning, Network coding, Network Capacity, Traffic Classification

This paper is focused on broadband wireless mesh networks based on OFDMA resource management, considering a realistic SINR model of the physical layer with a fine tuned power control at each node. A linear programing model using column generation leads to compute power efficient schedules with high network capacity. Correlation between capacity and energy consumption is analyzed as well as the impact of physical layer parameters -SINR threshold and path-loss exponent. We highlight that there is no significant tradeoff between capacity and energy when the power consumption of idle nodes is important. We also show that both energy consumption and network capacity are very sensitive to the SINR threshold variation.

- by anis ouni
- •
- Linear Programming, Wireless Mesh Networks, Energy Consumption, Computer Model

The influence of background wind flow on the dispersion of carbon monoxide (CO) was investigated over a onemonth period in two street canyons of differing geometry in the city of York, UK. Electrochemical sensors were used to measure CO concentrations at various heights and locations along each canyon. Six ultrasonic anemometers were used to measure the airflow and turbulence within one of the canyons. A seventh anemometer measured the above-roof (or background) winds at approximately twice the street building height. Bi-directional traffic flow was measured in each street using the Split, Cycle and Offset Optimisation Technique (SCOOT) system. The investigation indicates that differences in the street geometry and the background winds result in contrasting in-canyon wind flows and dispersion characteristics. Whilst there is evidence of a single cross canyon vortex in one street canyon for certain background wind directions, there are also a number of three-dimensional (3D) flow structures formed in the canyon due to the influence of flow channelling, both within the canyon and from adjoining side streets. For background winds with a strong perpendicular component relative to the canyon axes, the mean CO concentrations on the leeward side of the street canyons were on average, a factor of two greater than on the windward side. This feature can be attributed to the formation of vertical and horizontal vortices. However, when the concentrations were normalised by the background wind speed and total traffic flow, a three-fold difference exists between the windward and leeward sides of the street canyon. Evidence of flow channelling and helical flow regimes was also detected for background flows with a component parallel to the canyon axes. The difference in mean CO concentrations between the two street canyons was approximately two-fold, with the highest mean concentrations in the narrower canyon, which has a smaller crosssectional area. r

In this paper, we describe a new alternative control approach for indirectly connected district heating substations. Simulations results showed that the new approach results in an increased DT across the substation. Results were obtained for both ideal and non-ideal operation of the system, meaning that less water must be pumped through the district heating network, and a higher overall fuel efficiency can be obtained in the district heating power plants. When a higher fuel efficiency is achieved, the usage of primary fuel sources can be reduced. Improved efficiency also increases the effective heat transfer capacity of a district heating network, allowing more customers to be connected to an existing network without increasing the heating plant or network capacity.

- by Jan A van Deventer and +2
- •
- Engineering, Thermodynamics, Economics, Heat Transfer

Wireless mesh networks (WMNs) consist of mesh routers and mesh clients, where mesh routers have minimal mobility and form the backbone of WMNs. They provide network access for both mesh and conventional clients. The integration of WMNs with other networks such as the Internet, cellular, IEEE 802.11, IEEE 802.15, IEEE 802.16, sensor networks, etc., can be accomplished through the gateway and bridging functions in the mesh routers. Mesh clients can be either stationary or mobile, and can form a client mesh network among themselves and with mesh routers. WMNs are anticipated to resolve the limitations and to significantly improve the performance of ad hoc networks, wireless local area networks (WLANs), wireless personal area networks (WPANs), and wireless metropolitan area networks (WMANs). They are undergoing rapid progress and inspiring numerous deployments. WMNs will deliver wireless services for a large variety of applications in personal, local, campus, and metropolitan areas. Despite recent advances in wireless mesh networking, many research challenges remain in all protocol layers. This paper presents a detailed study on recent advances and open research issues in WMNs. System architectures and applications of WMNs are described, followed by discussing the critical factors influencing protocol design. Theoretical network capacity and the state-ofthe-art protocols for WMNs are explored with an objective to point out a number of open research issues. Finally, testbeds, industrial practice, and current standard activities related to WMNs are highlighted.

- by Ian Akyildiz
- •
- Engineering, Technology, Remote Sensing, Computer Networks

Providing high capacity in GSM networks at low costs using existing macrocells is of increasing importance in the near future due to the competition between operators. This paper shows that by applying frequency hopping in combination with an advanced frequency planning method, Multiple Reuse Patterns (MRP), very high traffic levels in the existing macrocells can be supported. Field experience from live networks shows that an average frequency reuse factor as low as 7.5 is possible without negatively affecting the network quality. Thus, the network capacity can be doubled compared to a non hopping network with reuse 4/12 using 10 MHz frequency spectrum. In a macrocell, it is possible to carry as much as 43 Erlang at 2% blocking.

- by Salum Nasser
- •
- Negative Affect, Field Experiment, Network Capacity

To my parents "I do not know what I may appear to the world; but to myself I seem to have been only like a boy playing on the seashore, and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary,... more

- by Adrian Popescu
- •
- Network Capacity, QoS Routing, Overlay Network

A major goal of the next-generation wireless communication systems is the development of a reliable high-speed wireless communication system that supports high user mobility. They must focus on increasing the link throughput and the network capacity. In this paper a novel, spectral efficient system is proposed for generating and transmitting twodimensional (2-D) orthogonal frequency division multiplexing (OFDM) symbols through 2-D inter-symbol interference (ISI) channel. Instead of conventional data mapping techniques, discrete finite Radon transform (FRAT) is used as a data mapping technique due to the increased orthogonality offered. As a result, the proposed structure gives a significant improvement in bit error rate (BER) performance. The new structure was tested and a comparison of performance for serial one-dimensional (1-D) Radon based OFDM and parallel 2-D Radon based OFDM is made under additive white Gaussian noise (AWGN), flat, and multi-path selective fading channels conditions. It is found that Radon based parallel 2-D OFDM has better speed and performance than serial 1-D Radon based OFDM.

- by Abbas Kattoush
- •
- Mechanical Engineering, Digital Signal Processing, Fading Channel, Bit Error Rate

Multicast is a key technology that provides efficient data communication among a set of nodes for wireless multi-hop networks. In sensor networks and MANETs, multicast algorithms are designed to be energy efficient and to achieve optimal route discovery among mobile nodes, respectively. However, in wireless mesh networks, which are required to provide high quality service to end users as the "last-mile" of the Internet, throughput maximization conflicting with scarce bandwidth has the paramount priority. We propose a Level Channel Assignment (LCA) algorithm and a Multi-Channel Multicast (MCM) algorithm to optimize throughput for multi-channel and multiinterface mesh networks. The algorithms first build a multicast structure by minimizing the number of relay nodes and hop count distances between the source and destinations, and use dedicated channel assignment strategies to improve the network capacity by reducing interference. We also illustrate that the use of partially overlapping channels can further improve the throughput. Simulations show that our algorithms greatly outperform the single-channel multicast algorithm. We observe that MCM achieves better throughput and shorter delay while LCA can be realized in distributed manner.

- by Li Xiao
- •
- Mobile Computing, Data Communication, Network Protocols, Sensor Network

In this paper we analyse the performance of multiple relay channels when multiple antennas are deployed only at relays. We apply two antenna diversity techniques at relays, namely maximum ratio combining (MRC) on receive and transmit beamforming (TB). We show that for both decode-and-forward and amplifyand-forward relaying protocols, with K relays the network can be decomposed into K diversity channels each with a different channel gain, and that the signals can be effectively combined at the destination. We assume that the total number of antennas at all relays is fixed at N. With a reasonable power constraint at the relays, the network capacity will be lower bounded by that of N relay channels each with single antenna, and upper bounded by that of single relay channel with N antennas.

This review of literature will navigate through proven model specifications that estimate delay as a function of investment in a logical airport network. Then, drawing from research in network and spatial science, I discern one way to index network neighbors that captures the spatial interaction between airports. The following literature reveals how to restructure static geographic distributions of investment at airports for network spatial analysis, and ultimately shows what properties are requisite for network spatial autocorrelation to assess the efficacy of those investments.

- by Holly Immler
- •
- Geography, Social Networks, Airline Economics, Airport Development

Understanding the performance of backoff algorithms in multihop ad hoc networks is a key feature to design efficient Medium Access Protocols for wireless networks. The 802.11 backoff algortihm, the Binary Exponential Backoff, and all the enhancement done to this algorithm are studied in depth in a single hop context. Very few analytical studies are done on 802.11 backoff algorithms in a multi-hop context due to the difficulty of modelling. In this paper we propose an analytical study, based on process algebra, of 4 backoff algorithms on 2 multi-hop scenarios. We evaluate the performance of each backoff algorithms from efficiency point of view and when possible from a fairness point of view.

- by Ali Shaheen
- •
- Mechanical Engineering, Digital Signal Processing, Fading Channel, Bit Error Rate

Kongesti di internet terjadi karena jumlah pengiriman data melebihi kapasitas router yang ada. Namun demikian, kenyataannya tidak setiap kongesti yang terjadi disebabkan karena hal tersebut. Sebagai contoh ketika kecepatan data dari satu pengirim jauh lebih tinggi dari pengirim yang lain karena mekanisme umpan balik yang tidak tepat, maka pengirim dengan kecepatan data jauh lebih rendah dapat dikatakan mengalami kongesti. Saat ini kongesti diatasi dengan melibatkan 2 mekanisme pengendalian, yaitu flow/congestion control di sumber pengirim data dan Active Queue Management (AQM) di router. AQM bertugas memberikan umpan balik kepada sumber pengirim sebagai indikasi dari tingkat kongesti di router. Sumber pengirim akan mengirimkan data ke jaringan sesuai dengan umpan bailk tersebut. Mekanisme ini dirasakan masih belum cukup untuk menuntaskan persoalan kongesti di internet. Untuk itu, dalam makalah ini akan dipaparkan sebab-sebab terjadinya kongesti, kelemahan dan teknik kendali kongesti, yang telah dikembangkan sampai saat ini. Untuk memperoleh gambaran respon sistem, digunakan Matlab untuk simulasi sistem.

- by Agung Harsoyo
- •
- Congestion Control, Flow Control, Network Capacity, AQM

This study takes a network theoretical perspective in its examination of innovation-based corporate entrepreneurship (ICE), focusing on how project-specific ties can form for nonroutine phenomena. A comparative case analysis of 246 interviews in twelve industry-leading global corporations identifies constructs associated with individual network capacity at the individual level, organizational network capacity at the organization level, and program network capacity at the ICE program level. In addition, we recognize the managerial facilitating roles of cultivator and broker. We develop propositions aimed at providing insights about the relationships among these constructs, and identify implications for managerial and ICE program responsibilities.

- by Gina O'Connor and +1
- •
- Marketing, Corporate Entrepreneurship, Business and Management, Network Theory

Abstract: A design of an automatic network capacity markets, often referred to asa bandwidth market, is presented. Three topics are investigated. First, anetwork model is proposed. The proposed model is based upon a trisectionof the participant roles into network users, network owners, and market middlemen.The network capacity is defined in a way that allows it to be traded,and to have

- by Lars Rasmusson
- •
- Financial Derivatives, Network Design, Network Capacity

The deployment of femtocells in a macrocell network is an economical and effective way to increase network capacity and coverage. Nevertheless, such deployment is challenging due to the presence of inter-tier and intra-tier interference, and the ad hoc operation of femtocells. Motivated by the flexible subchannel allocation capability of OFDMA, we investigate the effect of spectrum allocation in two-tier networks,

- by Marios Kountouris and +1
- •
- Distributed Computing, Open Access, Access Control, Network optimization

The expansion of telecommunication services has increased the number of users sharing network resources. When a given service is highly demanded, some demands may be unmet due to the limited capacity of the network links. Moreover, for such demands, telecommunication operators should pay penalty costs. To avoid rejecting demands, we can install more capacities in the existing network. In this paper we report experiments on the network capacity design for uncertain demand in telecommunication networks with integer link capacities. We use Poisson demands with bandwidths given by normal or log-normal distribution functions. The expectation function is evaluated using a predetermined set of realizations of the random parameter. We model this problem as a two-stage mixed integer program, which is solved using a stochastic subgradient procedure, the Barahona's volume approach and the Benders decomposition.

- by Rafael Andrade
- •
- Applied Mathematics, Telecommunication Networks, Network Design, Network Capacity

The perception of future wireless mesh network (WMN) deployment and usage is rapidly evolving. WMNs are now being envisaged to provide citywide "last-mile" access for numerous mobile devices running media-rich applications with stringent quality of service (QoS) requirements. Consequently, some current-day conceptions underlying application support in WMNs need to be revisited. In particular, in a large WMN, the dynamic assignment of users to Internet gateways will become a complex traffic engineering problem that will need to consider load peaks, user mobility, and handoff penalties. We propose QMesh, a framework for user-gateway assignment that runs inside the WMN, and is oblivious to underlying routing protocols. It solves the handoff management problem in a scalable distributed manner. We evaluate QMesh through an extensive simulation (mostly of VoIP), in two settings: (1) a real campus network, with user mobility traces from the public CRAWDAD dataset, and (2) a large-scale urban WMN. Simulation results demonstrate that QMesh achieves significant QoS improvements and network capacity increases compared to traditional handoff policies, and illustrate the need for intelligent gateway assignment within the mesh.

- by Israel Cidon
- •
- Routing, LISP, Quality of Service, Mobile Device

In wireless mesh networks, the end-to-end throughput of traffic flows depends on the path length, i.e., the higher the number of hops, the lower becomes the throughput. In this paper, a Fair End-to-end Bandwidth Allocation (FEBA) algorithm is introduced to solve this problem. FEBA is implemented at the Medium Access Control (MAC) layer of single-radio, multiple channels IEEE 802.16 mesh nodes, operated in a distributed coordinated scheduling mode. FEBA negotiates bandwidth among neighbors to assign a fair share proportional to a specified weight to each end-to-end traffic flow. This way traffic flows are served in a differentiated manner, with higher priority traffic flows being allocated more bandwidth on the average than the lower priority traffic flows. In fact, a node requests/grants bandwidth from/to its neighbors in a round-robin fashion where the amount of service depends on both the load on its different links and the priority of currently active traffic flows. If multiple channels are available, all of them are shared evenly in order to increase the network capacity due to frequency reuse. The performance of FEBA is evaluated by extensive simulations. It is shown that wireless resources are shared fairly among best-effort traffic flows, while multimedia streams are provided with a differentiated service that enables quality of service.

- by Claudio Cicconetti
- •
- Distributed Computing, Scheduling, Quality of Service, Wimax

This paper develops a conceptual model, based on a structural equation approach, for empirically investigating the role played by relational embeddedness in the process of creation of synergies of knowledge-related capabilities in strategic alliances (SAs). The theoretical model identifies an underlying latent construct; knowledge embeddedness and its antecedents: complementarity, compatibility, tacitness, trust, protectiveness, and coordination, which needs to be explicitly recognized and integrated in the theory of creation of synergies in SAs. While the individual importance of most of these variables has long been recognized in both SA and social exchange literature, their simultaneous effects have thus far been ignored. Embeddedness is hypothesized to be a full mediator of these effects on creation of synergies. Furthermore, absorptive capacity, network capacity, and collaborative know-how are proposed to moderate these effects.

- by Bo Nielsen
- •
- Business, Knowledge Management, Multidisciplinary, Absorptive Capacity

Purpose -Drawing on changes in the nature of European metropolitan development planning in general, and the example of the Randstad, in particular, the purpose of this paper is to argue for an improved interconnectedness between regions and their public and private sector agencies. These should be linked to "flows of social and economic interaction", and, as such, complement conventional notions of "bounded spaces" and "nested territorial jurisdictions". This is in response to the now crucial question for metropolitan planning of how to develop and renew effective institutional capacity to deal with the increasing spatial complexities at regional or metropolitan level. Design/methodology/approach -The paper is a case study-based theoretical review of types of metropolitan planning, drawing on original policy documents and interviews with relevant policymakers. Findings -It is shown that the answer to addressing the challenges of development planning at the city-regional level is not primarily to enlarge the steering powers of regional planning per se, but to broaden its strategic network capacity through enlarging the coordinative and communicative intelligence of the intermediate regional planning bodies. This allows better responsiveness to the evident transformation processes within spatial development planning as such, with a growing emphasis on a strategic element within it. This, again, is more in line with the changeability of urban space. Originality/value -The paper shows that the notion of spatial development planning has made a strong revival in the last ten years. It has been spatial planning that has attracted the key focus of debate, more so than adjacent policy-making sectors (economic policy in particular).

- by Johan Woltjer
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- Strategic Planning, Economic policy, Economic Development, Regional development

We present a new capacity estimation technique, called Cap-Probe. CapProbe combines delay as well as dispersion measurements of packet pairs to filter out samples distorted by cross-traffic. CapProbe algorithms include convergence tests and convergence speed-up techniques by varying probing parameters. Our study of CapProbe includes a probability analysis to determine the time it takes CapProbe to converge on the average. Through simulations and measurements, we found CapProbe to be quick and accurate across a wide range of traffic scenarios. We also compared Cap-Probe with two previous well-known techniques, pathchar and pathrate. We found CapProbe to be much more accurate than pathchar and similar in accuracy to pathrate, while providing faster estimation than both. Another advantage of CapProbe is its lower computation cost, since no statistical post processing of probing data is required.

- by Rohit Kapoor
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- Distributed Computing, Dispersion, Computer Software, Network Capacity

When investigating co-channel spatial reuse, typical studies on ad-hoc networks have adopted static, device-specific transmission/interference ranges regardless of the runtime environment. In this paper, we present an analytical framework to investigate co-channel spatial reuse in dense wireless ad-hoc networks based on RF propagation models for some common network topologies. We derive the minimum separation between simultaneous co-channel transmitters while maintaining desirable signal-noise-interference-ratio at receivers. Spatial reuse is characterized by the ratio between co-channel transmitter (T-T) and transmit-receiver (T-R) distances. Our results show that increasing transmission power improves spatial reuse in ambient noise dominated environments. However, in co-channel interference limited scenarios, increasing transmission power has little effect on spatial reuse. On the other hand, more simultaneous transmissions can be physically possible by decreasing the average T-R separation, independent of transmission power. Our results confirm that the popular practice of using static transmission/interference ranges leads to an oversimplified model that is unable to accurately characterize the spatial reuse (and consequently aggregate network capacity) in such ad-hoc networks.

- by Sumit Roy
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- Network Capacity, Ad hoc network, Network Topology, Wireless Ad Hoc Network

Many techniques have been proposed in the last few years to address performance degradations in end-to-end congestion control. Although these techniques require parameter tuning to operate in different congestion scenarios, they miss the challenging target of both minimizing network delay and keeping goodput close to the network capacity. In this paper we propose a new mechanism, called Active Window Management (AWM), which addresses these targets by stabilizing the queue length in the network gateways. AWM acts on the Advertised Window parameter in the TCP segment carrying the acknowledge, but it does not affect the TCP protocol. The proposed technique is implemented in the network access gateways, that is, in the gateways through which both the incoming and outgoing packets related to a given TCP connection are forced to go, whatever the routing strategy used in the network. We show that when the access gateways implementing AWM are the bottleneck in the networks, TCP performance is very close to that of a pseudo constant bit rate protocol providing no loss, while network utilization is close to one.

- by Giovanni Schembra
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- Congestion Control, Queueing theory, Traffic control, Stability

We consider optimal control for general networks with both wireless and wireline components and time varying channels. A dynamic strategy is developed to support all traffic whenever possible, and to make optimally fair decisions about which data to serve when inputs exceed network capacity. The strategy is decoupled into separate algorithms for flow control, routing, and resource allocation, and allows each user to make decisions independent of the actions of others. The combined strategy is shown to yield data rates that are arbitrarily close to the optimal operating point achieved when all network controllers are coordinated and have perfect knowledge of future events. The cost of approaching this fair operating point is an end-to-end delay increase for data that is served by the network. Analysis is performed at the packet level and considers the full effects of queueing.

- by Drpc Drpc
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- Distributed Computing, Optimal Control, Heterogeneous Networks, Routing

Vertical handoffs between different wireless technologies usually lead to dramatic changes in the link capacity. A successful QoS solution for vertical handoffs must be able to fast track the capacity changes and agilely adapt the delivery rates and qualities of the ongoing applications. Though traditional AIMD-based source adaptation schemes (as found in TCP, TFRC, etc.) have been well designed for mild, gradual rate adjustments required by load fluctuations and network congestion, their response time is inadequate when the rate must be adjusted to the drastic network capacity changes that are typical in vertical handoff scenarios. To expedite the response to such changes, we propose in this paper two adaptive algorithms, named the Fast Rate Adaptation (FRA) and Early Rate Reduction (ERR), that are launched when the handoff is from low to high capacity (LOW-to-HIGH) or from high to low capacity (HIGH-to-LOW), respectively. We also propose two vertical handoff notification mechanisms to work with FRA and/or ERR, i.e. the Implicit Handoff Notification (IHN) and Explicit Handoff Notification (EHN). We show by simulation that our proposed schemes are able to provide better QoS support than the traditional AIMD based schemes during vertical handoffs.

A new approach for reliability-based optimization of water distribution networks is presented. The approach links a genetic algorithm ͑GA͒ as the optimization tool with the first-order reliability method ͑FORM͒ for estimating network capacity reliability. Network capacity reliability in this case study refers to the probability of meeting minimum allowable pressure constraints across the network under uncertain nodal demands and uncertain pipe roughness conditions. The critical node capacity reliability approximation for network capacity reliability is closely examined and new methods for estimating the critical nodal and overall network capacity reliability using FORM are presented. FORM approximates Monte Carlo simulation reliabilities accurately and efficiently. In addition, FORM can be used to automatically determine the critical node location and corresponding capacity reliability. Network capacity reliability approximations using FORM are improved by considering two failure modes. This research demonstrates the novel combination of a GA with FORM as an effective approach for reliability-based optimization of water distribution networks. Correlations between random variables are shown to significantly increase optimal network costs.

- by Angus Simpson
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- Environmental Engineering, Civil Engineering, Algorithms, Monte Carlo Simulation