Amount Of Network Resources Research Articles

Routing, Modulation Format, Spatial Lane, and Spectrum Block Assignment in Static Spatial Channel Networks

Spatial channel networks (SCNs) and related key technologies have been proposed to increase the capacity and flexibility of optical networks. We define the network resource allocation problem in a static SCN as the routing, modulation format (MF), spatial lane, and spectrum block assignment (RMSSA) problem and try to solve it. In this paper, we derive the relationship between the traffic bit rate, the transmission distance of optical channels, and MFs in SCNs, and obtain the adoption method of MFs. In addition, we introduce conversion nodes (CNs) into SCNs to perform a modulation format conversion (MFC) for more efficient use of network resources. Moreover, the RMSSA problem in static SCNs is modeled, and heuristic spatial lane and spectrum block minimization based on simulated annealing (LBMSA) algorithm is proposed to solve the RMSSA problem. Simulation results show that when the throughput of SCNs is small, the LBMSA algorithm can carry traffic requests with the least amount of network resources and maximize the network resource utilization. When the network throughput is high, the LBMSA algorithm is more inclined to carry all requests rather than efficient transmission. We also show that network resource utilization can be improved with the LBMSA algorithm by setting CNs to perform the MFC.

Calculating algorithm of service quality statistical parameters for asynchronous network subscribers

It is often necessary to determine statistical parameters that characterize the quality of service on the network by managing when designing computer networks using the concept of virtual connections with bypass directions. In many ways, the attainable level of quality of the services provided is determined at the stage of network design, when decisions was made regarding the subscriber capacity of stations, the capacity of bundles of trunk lines, the composition and volume of telecommunication services provided. Despite constant progress in the field of network technologies, the problem of determining the necessary amount of network resources and ensuring the quality of user service remains relevant. In this regard, this article discusses a broadband digital network with service integration, based on an asynchronous network in which an iterative method implemented. Here the flow distribution is determined by the route matrix, and the load distribution between the nodes of each pair of nodes made through the path tree obtained on the matrix of routes when calculating this pair. At the same time, an algorithm has been built for allow optimal allocation of channel resources between circuit switching and packet switching subnets within an asynchronous network.

Uma Abordagem para Mitigar Ataque Blackhole em Redes Tolerantes a Atrasos e Desconexões utilizando Múltiplos Caminhos

As redes tolerantes a atrasos e desconexões (Delay Tolerant Networks – DTNs) são redes que não precisam de infraestrutura e utilizam da locomoção dos seus nós para se comunicar. Todavia, ataques do tipo Buracos Negros (do inglês, Blackhole) consistem em uma ameaça para o funcionamento destas redes ao descartar pacotes de usuários legítimos. Na literatura há esforços para solucionar o ataque blackhole em DTNs. No entanto, as formas implementadas consomem uma grande quantidade de recursos da rede, pois funcionam por meio da geração de cópias da mensagem. Neste contexto, este trabalho apresenta uma abordagem de mitigação que se utiliza da Mojette e múltiplos caminhos para fragmentar, enviar e recuperar o dado e sem o alto desgaste da rede. A abordagem foi desenvolvida utilizando a IDE (Integrated Development Environment) Eclipse em conjunto com o simulador de ambiente de rede oportunista The ONE (The Opportunistic Network Environment Simulator). Nesse ambiente foram desenvolvidos dois cenários com diferentes situações, a fim de realizar três simulações, visando a avaliar a abordagem que tem como objetivos transmitir e recuperar o pacote ainda que existam descartes. Os resultados obtidos por meio das simulações revelam que a abordagem apresenta uma taxa de remontagem de no mínimo 75%, ainda que a taxa de pacotes perdidos seja de 62,50%.

Enhancement of the adaptive routing tensor model in the infocommunication network with providing quality of experience by the R-factor

The object of research is the routing processes and ensuring the quality of experience in the infocommunication network. To conduct research an improvement of the adaptive routing tensor model in an infocommunication network with quality of experience by the R-factor is proposed. The basis was a floe-based routing model that took into account possible packet losses caused by congestion of network elements and was represented by the conditions for implementing a multipath routing strategy, conditions of the flow conservation and conditions for preventing overload of communication links. To obtain in an analytical form the conditions for ensuring the quality of experience in terms of the R-factor, a tensor description of the infocommunication network is carried out. This allowed obtaining of analytical expressions for calculating the average end-to-end delay and the probability of packet loss, which were used to formulate the QoE conditions in terms of the R-factor.In the framework of the proposed model, solving the technological problem of adaptive routing solutions are reduced to solving the optimization problem of nonlinear programming for calculating route variables. The introduced optimality criterion allowed it possible to ensure the adaptive nature of route decisions, when an increase in QoE requirements led to an increase in the amount of network resource used. To solve the problem, methods of mathematical programming were used, which are implemented in the MatLab package.A study on a fragment of the infocommunication network made it possible to evaluate the adequacy and effectiveness of the proposed model. Using the obtained research results, it was possible to ensure the fulfillment of the specified QoE requirements in terms of the R-factor for the services provided to end users. Using the proposed model is characterized by high efficiency on load balancing across multiple routes in the infocommunication network. This was evidenced by the fact that at a given value of the R-factor, with an increase in the intensity of traffic entering the infocommunication network, there was a gradual increase in the number of routes involved. In other words, the network resource was distributed evenly and efficiently by 7–10 % relative to known analogues, which, when solving the same problem, immediately use all possible routes.

Parametric Optimization of Packet Transmission with Resending Packets Mechanism

The data transmission process is modelled by a Markov closed queuing network, which consists of two stations. The primary station describes the process of sending packets over a lossy channel by means of a finite and single-channel queue. The auxiliary station, being a multichannel queuing system, accumulates packets lost by the primary station and forwards them back for retrial. The transmission rate at the primary station and the retrial rate at the auxiliary station are in the specified ranges and are subject to optimization in order to minimize the time of successful delivery and the amount of network resources used. The explicit expressions for these characteristics are derived in the steady-state mode in order to formulate the problem of bi-criterion optimization. The optimal policies are established in two scenarios: the first problem is to minimize the average time of successful transmission with limited resources; the second problem is to minimize the consumption of network resources under the constraint on the time for successful transmission. The set of Pareto-optimal policies is obtained by solving the problem of minimization of the augmented functional. The quality characteristics of approximate solutions that do not take into account the service rate in the auxiliary system are analyzed.

Cache Replacement Based on Distance to Origin Servers

The number of users downloading video content on the Internet has dramatically increased recently, and obtaining huge rich content items, e.g., movie files, is becoming a popular application of the Internet. The transmission bandwidth consumed by delivering rich content is enormous. Therefore, it is urgent for Internet service providers to design an efficient delivery system that minimizes the amount of network resources consumed. Content delivery networks are widely used to reduce the flow hop length and the response time when obtaining content items. To improve the cache efficiency, various methods of replacing caches have been proposed, with the target of improving the cache hit ratio. The effect of reducing the traffic load on network links by delivering content items from caches depends on the distance from the origin server to the users. However, many existing methods do not consider the origin server distance. To maximize the effect of reducing the link load obtained by caches, we propose here a cache-replacement policy based on the hop distance to the origin servers. To simplify the caching algorithm, we divide the storage capacity of cache severs into multiple virtual caches and manage content items separately on the basis of the hop distance to origin servers. We also propose an optimal method for designing the capacities of virtual caches that maximizes the total expected reduction of flow hop length. Through numerical evaluation, we show that the proposed method can decrease the average link load by about 10% compared with the normal least recently used.

Adaptive Fractional Repetition Codes for Dynamic Storage Systems

Node recovery is a challenging task in erasure-coded storage systems, which involves a considerable amount of network resources. The efficacy of failure recovery is measured by various metrics, such as repair bandwidth and computational complexity. This letter focuses on fractional repetition (FR) codes, which are a family of codes that provide uncoded exact repairs with minimum repair bandwidth. We consider the usage of FR codes in dynamic storage systems, where the system parameters can vary over time. Specifically, we introduce adaptive fractional repetition codes that can effectively adapt to system changes. The proposed codes allow update of systems without the need for frequent reconfigurations. Moreover, explicit code constructions for both homogeneous and heterogeneous storage systems are presented.

Estimation of Storage using Jitter incorporated Channelization

In video applications the storage requirement is considerably large among all the multimedia objects and thus they require large amount of network resources especially storage space and bandwidth. Here, we discuss a mathematical model to estimate the buffer space required to provide the video data to users without break and hiccups. For doing this, we divide the given physical channel (PC) into logical channels (LCs) using time-division multiplexing (TDM) approach. The data rate, also known as bandwidth, can be allocated to the LCs uniformly or non-uniformly. In [14], it is reported that allocating bandwidth non-uniformly to the LCs needs less buffer space. Therefore, the bandwidth is allocated non-uniformly to the logical channels, which in turn reduces system cost; thus, making the video services cheaper. The proposed work estimates the buffer storage by incorporating the jitter delay. The buffer storage is modeled as a random variable (rv) and its probability density function (PDF) is developed. The simulation results are obtained by dividing a physical channel into three, five, eight, and ten logical channels. This study may be used in several applications for example, cable TV, news-on-demand, video-on-demand.

Coordinated Tethering Over White Spaces

Coordinated tethering over a white-space spectrum is investigated herein to increase mobile broadband spectrum efficiency in densely populated areas. This paper proposes an algorithm for operator-controlled tethering over white spaces. The proposed approach does not add to the existing infrastructure but instead allows the individual nodes to act as “hotspots” and to tether data to and from other nodes. The proposed algorithm iteratively clusters the nodes into hotspots and slaves and allocates resources to maximize spectrum utility. The proposed method's dynamic characteristics allow cellular systems to hierarchically evolve in dense areas as necessary. A signaling framework for node-to-node and base-station-to-node communication that enables such operator-controlled tethering is also presented. Simulation results show that given a fixed amount of network resources, the proposed algorithm can significantly increase the number of supported users.

Novel methods for virtual network composition

Network virtualization has been proposed as a technology that aims to solve the Internet ossification. Central to the network virtualization is a virtual network composition mechanism providing an efficient mapping of virtual nodes and links onto appropriate physical resources in the network infrastructure.This paper proposes a novel backtracking heuristic algorithm for virtual network composition. Based on this algorithm, two approaches with two different objectives are presented. The first approach (Backtracking-CR) aims to compose a virtual network using the least amount of network resources, while the second (Backtracking-LB) applies load balancing for virtual network composition. Furthermore, a linear programming approach that optimizes the virtual network composition with an objective of using the least amount of network resources is presented and used to bench mark the heuristic algorithm. Simulation results show that using less network resources by applying linear programming or Backtracking-CR does not produce higher number of successfully mapped virtual networks when is compared to load balancing approach. Results also show that the proposed heuristic algorithm is scalable to large physical and virtual networks with respect to the computation time.

Analyzing influence of network topology on designing ISP-operated CDN

The transmission bandwidth consumed by delivering rich content, such as movie files, is enormous, so it is urgent for ISPs to design an efficient delivery system minimizing the amount of network resources consumed. To serve users rich content economically and efficiently, an ISP itself should provide servers with huge storage capacities at a limited number of locations within its network. Therefore, we have investigated the content deployment method and the content delivery process that are desirable for this ISP-operated content delivery network (CDN). We have also proposed an optimum cache server allocation method for an ISP-operated CDN. In this paper, we investigate the properties of the topological locations of nodes at which cache placement is effective using 31 network topologies of actual ISPs. We also classify the 31 networks into two types and evaluate the optimum cache count in each network type.

A study of overheads and accuracy for efficient monitoring of wireless mesh networks

IEEE 802.11-based wireless mesh networks are being increasingly deployed in enterprize and municipal settings. A lot of work has been done on developing measurement-based schemes for resource provisioning and fault management in these networks. The above goals require an efficient monitoring infrastructure to be deployed, which can provide the maximum amount of information regarding the network status, while utilizing the least possible amount of network resources. However, network monitoring involves overheads, which can adversely impact performance from the perspective of the end user. The impact of monitoring overheads on data traffic has been overlooked in most of the previous works. It remains unclear as to how parameters such as number of monitoring agents, or frequency of reporting monitoring data, among others, impact the performance of a wireless network. In this work, we first evaluate the impact of monitoring overheads on data traffic, and show that even small amounts of overhead can cause a large degradation in the network performance. We then explore several different techniques for reducing monitoring overheads, while maintaining the objective (resource provisioning, fault management, and others) that needs to be achieved. Via extensive simulations and experiments, we validate the efficiency of our proposed approaches in reducing overheads, their impact on the quality of data collected from the network, and the impact they have on the performance of the applications using the collected data. Based on results, we conclude that it is feasible to make the current monitoring techniques more efficient by reducing the communication overheads involved while still achieving the desired application-layer objectives.

Modeling of Buffer Storage in Video Transmission

In video applications, the storage requirement is considerably large and hence they require large amount of network resources for their transmission. For transmitting the videos through a physical channel, there are two types of channelization-constant bandwidth and variable bandwidth channelization. It has been reported that using variable bandwidth channelization the buffer storage requirement is less than that of constant bandwidth channelization. Therefore, using variable bandwidth channelization a stochastic model is proposed for estimating the buffer storage so that the continuous delivery of the video data can be provided to the users.

A Framework for Transaction-Level Quality of Service for M-Commerce Applications

In the emerging wireless Internet environment involving m-commerce and other mobile applications, an increasing number of users are likely to adopt mobile transactions. These transactions may have very diverse requirements and some of them may require a significant amount of network resources and/or bounded delays. One of many unique characteristics of transactions involving a financial value is the criticality of its completion. The unique requirements of mobile transactions necessitate the introduction of new metrics for quality-of-service. So far, most of the quality-of-service research in wireless networks has focused on call or connection- level QoS. In this paper, we propose a framework to support QoS requirements of mobile transactions by resource allocation at the connection level, transaction level, and a combination of connection and transaction levels. To measure the QoS effectiveness of mobile transactions, two new metrics, transaction completion probability and transaction response time, are introduced. Simulation and analytical models are used for computing different metrics for transaction performance under varying network and traffic conditions. The results show that the balanced transaction and connection level resource allocation can improve the probability of transactions completion and resource utilization. This improvement is at the cost of slightly increased processing overload, which is dependent on both the group size and number of transactions during a connection.

A Zone-Based Approach for Scalable Dynamic Traffic Grooming in Large WDM Mesh Networks

Dynamic traffic grooming in optical mesh networks is one of the most important and practical problems for designing wavelength-division-multiplexing networks. Most of the previous work solves this problem by applying the Dijsktra's algorithm on an auxiliary graph. Although those algorithms may give a good performance since they have a global view of the whole network, they are very time consuming and thus cannot be applied in large networks. Therefore, to the best of our knowledge, for the first time, we propose a heuristic algorithm to reduce the required computations by minimizing the size of the graph. We compare our algorithm with existing algorithms by extensive simulations in a typical 24-node mesh networks. The results demonstrate that our algorithm can significantly reduce the computational complexity, typically by a few tens times. Despite its simplification, our algorithm outperforms existing algorithms by large margins since it can easily avoid lightpaths that consume a large amount of network resources

The relationship of mentoring and network resources with career success in the Chinese organizational environment

The relationship of mentoring and network resources, the two components of social capital, with career success was investigated in a sample of 113 Chinese white-collar workers. The findings suggested that the prevalence of mentoring in the Chinese workplace is substantially higher than in the Anglo-Saxon workplace, and that Chinese employees do not distinguish their network ties or Guanxi into expressive and instrumental. These results were in line with the presumption that mentoring is an integral part of the Chinese culture and with the view that network ties or Guanxi in the Chinese society cannot exist in a purely instrumental form. In contrast to hypotheses, however, the findings suggest a limited relationship between social capital and career success. In particular, the amount of mentoring, participants reported they had received, was related to their intrinsic career success but not to their extrinsic career success; and the amount of network resources or Guanxi was related neither to extrinsic nor to intrinsic career success. These results were largely at odds with the accumulated knowledge on the benefits of social capital for career success. The findings are discussed with respect to the changing nature of the Chinese business and organizational environment, and their implications for human resource practices.

Evaluation of packet loss impairment on streaming video

Video compression technologies are essential in video streaming application because they could save a great amount of network resources. However compressed videos are also extremely sensitive to packet loss which is inevitable in today's best effort IP network. Therefore we think accurate evaluation of packet loss impairment on compressed video is very important. In this work, we develop an analytic model to describe these impairments without the reference of the original video (NR) and propose an impairment metric based on the model, which takes into account both impairment length and impairment strength. To evaluate an impaired frame or video, we design a detection and evaluation algorithm (DE algorithm) to compute the above metric value. The DE algorithm has low computational complexity and is currently being implemented in the real-time monitoring module of our HDTV over IP system. The impairment metric and DE algorithm could also be used in adaptive system or be used to compare different error concealment strategies.

Dynamic Allocation of Resources to Virtual Path Agents

One of the major problems faced in operating large networks is the enormous amount of processing and communications overhead required for setting up and tearing down the large number of connections maintained by the network. ATM and MPLS aim at solving these problems via the Virtual Path (VP) mechanism which is used to group together the connections. When a need for setting up a connection rises, the request and its resource allocation are processed by the VP agent and not by the network, thus reducing the processing cost significantly. An important question in the design of these networks is the amount of network resources to be dynamically allocated to and held by the VP agents; too high allocation will result with bandwidth resource waste, while too low allocation will result with heavy connection set-up and tear-down processing load. In this paper we deal with this problem, and at deriving simple operational rules to determine the amount of bandwidth resources to be held by the various VP agents, while balancing between bandwidth waste and connection processing overhead. We formulate the resource allocation problem by accounting both for bandwidth utilization and for connection processing constraints. Recognizing the complexity of the problem, we use a decomposition approach in which we first analyze the single link problem and then propose to use this solution as a building block in constructing algorithms for the whole network. For the single link problem we realize that the pure problem is too complex and thus formulate an approximate model and derive the optimal allocation for it. The optimal rule is expressed as a closed-form square-root allocation. Extensive numerical examination shows that the rule proposed yields very efficient allocations. For the full network problem, we propose to capitalize on the closed form structure of the single link problem solution and use it in devising algorithms for the whole network.

Traffic engineering in multigranularity heterogeneous optical WDM mesh networks through dynamic traffic grooming

In this article we investigate the problem of efficiently provisioning connections of different bandwidth granularities in a heterogeneous WDM mesh network through dynamic traffic grooming schemes under traffic engineering principles. Due to the huge amount of traffic a WDM backbone network can support and the large geographic area it can cover, constructing and upgrading such an optical WDM network can be costly. Hence, it is extremely important for network operators to apply traffic engineering strategies to cost-effectively support different bandwidth granularity services using only the appropriate amount of network resources. This requires an optical WDM network to have multigranularity switching capability, and such a network tends to be a multivendor heterogeneous network. However, WDM network heterogeneity increases the difficulty and challenge of efficient traffic provisioning. In this article we present different TE issues that need to be carefully considered in such an optical WDM network, and propose possible solutions and extensions for the generalized multiprotocol label switching optical network control plane. We extend an existing generic graph model to perform efficient traffic grooming and achieve different TE objectives through simple shortest path computation algorithms. We show that our approach is very practical and very suitable for traffic engineering in a heterogeneous multigranularity optical WDM mesh network.

A Delay-Constrained Least-Cost Multicast Routing Heuristic for Dynamic Multicast Groups

Many new multimedia applications involve dynamic multiple participants, have stringent end-to-end delay requirement and consume large amount of network resources. In this paper, we propose a new dynamic delay-constrained least-cost multicast routing algorithm (DDCLCMR) to support these applications. When group membership changes, the existing multicast tree is perturbed as little as possible. Simulation results show that DDCLCMR performs very well in terms of cost for both, static and dynamic multicast groups, when compared to the best multicast algorithms known. Our evaluation of the cost performance of the algorithms showed that DDCLCMR is always within 10% from BSMA which has the best cost performance among all the proposed delay-constrained static multicast heuristics, while NAIVE, the well-known dynamic multicast routing algorithm, is up to 70% worse than BSMA in some cases.