Enhancement of TCP over wired/wireless networks with packet loss classifiers inferred by supervised learning

TCP is suboptimal in heterogeneous wired/wireless networks because it reacts in the same way to losses due to congestion and losses due to link errors. In this paper, we propose to improve TCP performance in wired/wireless networks by endowing it with a classifier that can distinguish packet loss causes. In contrast to other proposals we do not change TCP’s congestion control nor TCP’s error recovery. A packet loss whose cause is classified as link error will simply be ignored by TCP’s congestion control and recovered as usual, while a packet loss classified as congestion loss will trigger both mechanisms as usual. To build our classification algorithm, a database of pre-classified losses is gathered by simulating a large set of random network conditions, and classification models are automatically built from this database by using supervised learning methods. Several learning algorithms are compared for this task. Our simulations of different scenarios show that adding such a classifier to TCP can improve the throughput of TCP substantially in wired/wireless networks without compromizing TCP-friendliness in both wired and wireless environments.     

Performance Analysis of Wireless Network with Opportunistic Spectrum Sharing via Cognitive Radio Nodes

Cognitive radio (CR) is found to be an emerging key for efficient spectrum utilization. In this paper, spectrum sharing among service providers with the help of cognitive radio has been investigated. The technique of spectrum sharing among service providers to share the licensed spectrum of licensed service providers in a dynamic manner is considered. The performance of the wireless network with opportunistic spectrum sharing techniques is analyzed. Thus, the spectral utilization and efficiency of sensing is increased, the interference is minimized, and the call blockage is reduced.     

A Dynamic Packet Recovery Mechanism for Realtime Service in Mobile Computing Environments

This paper analyzes the characteristics of packet losses in mobile computing environments based on the Gilbert model and then describes a mechanism that can recover the lost audio packets using redundant data. Using information periodically reported by a receiver, the sender dynamically adjusts the amount and offset values of redundant data with the constraint of minimizing the bandwidth consumption of wireless links. Since mobile computing environments can be often characterized by frequent and consecutive packet losses, loss recovery mechanisms need to deal efficiently with both random and consecutive packet losses. To achieve this, the suggested mechanism uses relatively large, discontinuous exponential offset values. That gives the same effect as using both the sequential and interleaving redundant information. To verify the effectiveness of the mechanism, we extended and implemented RTP/RTCP and applications. The experimental results show that our mechanism, with an exponential offset, achieves a remarkably low complete packet loss rate and adapts dynamically to the fluctuation of the packet loss pattern in mobile computing environments.     

Resilient multicast using overlays

We introduce Probabilistic Resilient Multicast (PRM): a multicast data recovery scheme that improves data delivery ratios while maintaining low end-to-end latencies. PRM has both a proactive and a reactive components; in this paper we describe how PRM can be used to improve the performance of application-layer multicast protocols especially when there are high packet losses and host failures. Through detailed analysis in this paper, we show that this loss recovery technique has efficient scaling properties-the overheads at each overlay node asymptotically decrease to zero with increasing group sizes. As a detailed case study, we show how PRM can be applied to the NICE application-layer multicast protocol. We present detailed simulations of the PRM-enhanced NICE protocol for 10 000 node Internet-like topologies. Simulations show that PRM achieves a high delivery ratio (>97%) with a low latency bound (600 ms) for environments with high end-to-end network losses (1%-5%) and high topology change rates (5 changes per second) while incurring very low overheads (<5%).     

A novel shared-path protection algorithm with correlated risk against multiple failures in flexible bandwidth optical networks

In this paper, to decrease the traffic loss caused by multiple link failures, we consider the correlated risk among different connection requests when both the primary and backup paths are routed and assigned spectrum. Therefore, a novel shared-path protection algorithm is developed, named shared-path protection algorithm with correlated risk (SPP_CR), in flexible bandwidth optical networks. Based on the correlated risk, the routing can be diverse and the sharing in backup spectral resource will be restricted by SPP_CR algorithm, then the dropped traffic caused by simultaneous multiple failures between primary and backup path can be efficiently decreased. Simulation results show that, SPP_CR algorithm (i) achieves the higher successful service ratio (SSR) than traditional shared-path protection (SPP), shared-path protection with dynamic load balancing (SPP_DLB) and dedicated path protection (DPP); (ii) makes a better tradeoff in blocking probability, protection ratio (PR), average frequency slots consumed (AFSC) and redundancy ratio (RR) than SPP, SPP_DLB and DPP algorithms.     

Extensible signaling for temporal resource sharing

The Internet is rapidly evolving from a network that provides basic best-effort communication service to an infrastructure capable of supporting complex value-added services. These services typically have multiple fluffs with interdependent resource requirements. These dependencies provide opportunities to share the same set of resources among related flows over time leading to significant resource gains. We call this type of sharing temporal resource sharing. Exploiting temporal sharing requires support in the signaling protocol that performs resource allocation for the related flows. We examine the problem of supporting temporal sharing in a signaling protocol. This paper makes the case that temporal sharing support must be designed to be extensible, so that service providers can define and implement new sharing behaviors without having to modify the signaling protocol. We motivate the need for an extensible design by showing that the range of possible temporal sharing behaviors is large and supporting the most general forms of temporal sharing is computationally expensive. We then present a design for extensible signaling support for temporal sharing. We have implemented the temporal sharing design presented in this paper in the Beagle signaling protocol. We present an evaluation of the Beagle design and contrast it with other signaling protocols like RSVP and Tenet-2     

Multiple link failure recovery in survivable optical networks

Survivability is of critical importance in high-speed optical communication networks. A typical approach to the design of survivable networks is through a protection scheme that pre-determines and reserves backup bandwidth considering single/double link failure scenarios. In this article, a greedy algorithm is presented to reserve backup bandwidth considering multiple (F > 2) link (SRLG) failure scenarios. A bandwidth-saving joint selection scheme of working and protection paths is presented for protection against random multiple-link failures under dynamic traffic. Simulation shows that the algorithm can achieve maximum sharing of backup bandwidth for protection against random multiple-link failure with significant amount of bandwidth saving.     

A loosely coupled vision for computational grids

Loosely coupled grids allow straightforward resource sharing because resources are accessed and exploited through de facto standard protocols and interfaces, similar to the Internet's early stages. The loosely coupled model allows easier, scalable, and compatible deployment at a lower global performance expense, compared to a tightly coupled alternative. Because we can apply the end-to-end principle only on both the client and server sides, we can build loosely coupled grid environments based only on Globus services and user-level middleware, while obtaining acceptable quality of service for both grid and local users, and fair resource sharing.     

Interoperability of EFCI and ER switches for ABR services in ATMnetworks

With the advances in switching technologies, explicit rate (ER) switches are becoming popular since they perform better than explicit forward congestion indication (EFCI) switches. In the transitional period, EFCI and ER switches may coexist in the same ATM network. Hence, the efficiency of various ER schemes should be reevaluated in the mixed EFCI-ER environment, not only in the homogeneous ER environment. Also, some important implications are observed in the heterogeneous environments. Because the location of an ER switch in the topology is critical to its performance, some placement rules, which describe how to place the ER switches for network operators, are developed in order to achieve a better performance of the network. The results presented should serve as an operational reference for service providers     

Optimal Logic for Multi-Channel Protective Systems During On-Line Maintenance

Protective systems have two kinds of failures: failed dangerous (FD) and failed-safe (FS). The former can lead to serious damage to the plant, while the latter can result in financial loss because of unnecessary protective actions. Frequently, protective system channels must be maintained and repaired during plant operation, ie, while they are in service. When this happens, one must choose whether the output of a channel being maintained should be set to the on or off position. On means the protective system protects against the FD failure, and is vulnerable to FS failures. We develop a systematic method to determine the output default values, and solve the more general problem of determining the optimal logic connections for the remaining channels. Analytic formulae are presented for transition failure rates are constant with time, and the channels are in voting configurations.     

D-HRSP: Dataset of helpful reviews for service providers

Most common services are now provided through mobile applications; thus, the importance of mobile application reviews has increased. Service providers and developers seek helpful reviews to find useful information to improve their services. However, with currently existing indicators, e.g., star rating systems, it is difficult to identify reviews that are directly related to the quality of the service. Thus, in this study, we defined helpful mobile application reviews for service providers and developers based on the components of an existing service quality evaluation model. We also provide the D-HRSP (dataset of helpful reviews for service providers), which is a labeled dataset that can be used to examine helpful reviews. We also report the experimental results obtained with simple natural language processing techniques and machine learning and deep learning classification models. The experimental results demonstrate that the proposed definition can help address real-life problems and create opportunities for additional research into the identification of helpful mobile application reviews.     

Competition in Parallel-Serial Networks

We study the efficiency implications of competition among profit-maximizing service providers in communication networks. Service providers set prices for transmission of flows through their (sub)network. The central question is whether the presence of prices will help or hinder network performance. We investigate this question by considering the difference between users' willingness to pay and delay costs as the efficiency metric. Previous work has demonstrated that in networks consisting of parallel links, efficiency losses from competition are bounded. Nevertheless, parallel-link networks are special, and in most networks, traffic has to simultaneously traverse links (or subnetworks) operated by independent service providers. The simplest network topology allowing this feature is the parallel-serial structure, which we study in this paper. In contrast to existing results, we show that in the presence of serial links, the efficiency loss relative to the social optimum can be arbitrarily large. The reason for this degradation of performance is the double marginalization problem, whereby each serial provider charges high prices not taking into account the effect of this strategy on the profits of other providers along the same path. Nevertheless, when there are no delay costs without transmission (i.e., latencies at zero are equal to zero), irrespective of the number of serial and parallel providers, the efficiency of strong oligopoly equilibria can be bounded by 1/2, where strong oligopoly equilibria are equilibria in which each provider plays a strict best response and all of the traffic is transmitted. However, even with strong oligopoly equilibria, inefficiency can be arbitrarily large when the assumption of no delay costs without transmission is relaxed.     

Energy aware cloud-edge service placement approaches in the Internet of Things communications

In recent years, applying Internet of Things (IoT) applications has significantly increased to facilitate and improve quality of human life activities in various fields such as healthcare, education, industry, economics, etc. The energy aware cloud-edge computing paradigm has developed as a hybrid computing solution to provide IoT applications using available cloud service providers and fog nodes for the smart devices and mobile applications. Since the IoT applications are developed in the form of several IoT services with various quality of service (QoS) metrics which can deploy on the cloud-edge providers with different resource capabilities, finding an efficient placement solution as one of challenging topics to be measured for IoT applications. The service placement issue arranges IoT applications on the cloud-edge providers with various capabilities of atomic services though sufficient different QoS factors to support service level agreement (SLA) contracts. This paper presents a technical analysis on the cloud-edge service placement approaches in IoT systems. The key point of this technical analysis is to identify substantial studies in the service placement approaches which need additional consideration to progress more efficient and effective placement strategies in IoT environments. In addition, a side-by-side taxonomy is proposed to categorize the relevant studies on cloud-edge service placement approaches and algorithms. A statistical and technical analysis of reviewed existing approaches is provided, and evaluation factors and attributes are discussed. Finally, open issues and forthcoming challenges of service placement approaches are presented.     

CE2RV: Commissioned energy-efficient virtualization for large-scale heterogeneous wireless sensor networks

The Internet of Things (IoT) comprises sensor networks, intelligent things, devices, and humans for heterogeneous services and applications. Energy constraints in conventional wireless networks impact IoT performance resulting in service failures. For reducing the adverse impact of energy, this article introduces a commissioned energy-efficient resource virtualization (CE2RV) scheme. This proposed scheme classifies the sensor nodes as fast and slow-depleting for identifying service failures. The fast-depleting nodes are discontinued from the service replications, and the remaining energy high-node-connected resources are identified. Such resources are virtualized for thwarting the existing energy failures over various services. The node classifications are performed using a tree-learning algorithm. The classifications are performed for node replacement and service virtualization under different energy depletion rates. This is required for preventing sensor network disconnections between the users and service providers. The classification is required for overcoming multiple virtualizations between common nodes across different service providers. The proposed scheme's performance is analyzed using the metrics of service disconnections, energy utilization, energy efficiency, and service delay.     

Wi-Fi网络资源共享现状及发展研究

目前,Wi-Fi网络资源共建共享已经成为全球通信业界广为流行的做法。为了了解国内三大运营商的Wi-Fi网络资源共享现状,对此进行了调查研究,指出三大运营商Wi-Fi网络资源共享中存在的问题,并根据国外运营商的共享情况对国内运营商Wi-Fi网络资源共享的未来做出了展望。     

一种网格资源优化分配方案

 本文提出了基于线性规划的网格异构资源分配问题的建模和求解方法.该方案综合考虑了资源分配问题的资源共享、作业优先级、作业对多种资源的依赖以及算法自身的策略等多种因素和约束条件.然后提出了网格环境下对独立作业进行网格资源分配的网格服务架构.实验表明基于线性规划的资源分配方法在速度和精确性两方面都是有效的,并且能保持高作业吞吐量.基于网格服务的架构也使该系统具有可扩展性和可伸缩性.     

Link-lifetime-based service restoration in optical datacenter network

Aiming at the correlated and cascading failures caused by large-scale disasters,a post-disaster service restoration scheme was proposed.This scheme utilized global service bandwidth concession and the limited lifetime of local links to mitigate resource crunch in the post-disaster network.According to their bandwidth and holding time requirements,the impacted services for restoration was prioritized firstly,then jointly employed anycast and manycast routing strategies to improve the service connectivity and bandwidth resource utilization.Simulation results show that the proposed scheme can significantly reduce the service loss ratio,effectively prolong the holding time of the impacted services and decrease the data flow loss ratio in the post-disaster network.     

A locally optimal handoff algorithm for cellular communications

The design of handoff algorithms for cellular communication systems based on mobile signal strength measurements is considered. The design problem is posed as an optimization to obtain the best tradeoff between the expected number of service failures and expected number of handoffs, where a service failure is defined to be the event that the signal strength falls below a level required for satisfactory service to the subscriber. Based on dynamic programming arguments, an optimal solution is obtained, which, though impractical, can be used as a benchmark in the comparison of suboptimal schemes. A simple locally optimal handoff algorithm is derived from the optimal solution. Like the standard hysteresis algorithm, the locally optimal algorithm is characterized by a single threshold. A systematic method for the comparison of various handoff algorithms that are akin to the receiver operating characteristic (ROC) curves of radar detection is presented. Simulation results show that the locally optimal algorithm outperforms the hysteresis algorithm, especially in situations where accurate prediction of signal strength is possible. A straightforward technique for adapting the locally optimal algorithm to changing environments is suggested. That natural adaptability is the algorithm's principle advantage over current approaches     

Data Service: Characteristics, Market Structure, and the Role of Operator

1　Introduction　Since the development of telecommunication technologymake the operator able to offer data service to subscribers inthe mid 1990s, operators of various countries have madeenormous efforts to develop data service. Currently, the ar gument on 3G ( 3rd Generation, International MobileTelecommunications 2000) focuses on how to find, develop,and popularize application services in data service markettoo. Some researchers propose that even NTT DoCoMo can n…