A Generic Quantitative Approach to the Scheduling of Synchronous Packets in a Shared Uplink Wireless Channel

The scheduling logic at the base station of a shared wireless medium supports time-dependent (synchronous) applications by allocating timely transmission grants. To this end, it must take into account not only the deadlines of the pending packets, but also the channel conditions for each potential sender, the requirements of nonsynchronous applications, and the packet retransmission strategy. With respect to these factors, we identify three scheduling scenarios and show that the scheduler logic faces a different challenge in addressing each of them. We then present a generic scheduling algorithm that translates all the factors relevant to each scenario into a common profit parameter, and selects the most profitable transmission instances.     

Increasing Lifetime and Fault Tolerance Capability in Wireless Sensor Networks by Providing a Novel Management Framework

The main application of wireless sensor networks is to monitor remote and dangerous areas that are inaccessible or difficult and or costly to reach by humans. This characteristic makes these networks be self-managed, face the challenges of fault tolerance and energy and network lifetime constraints due to non-renewable energy sources. In this paper, a management framework capable of providing and increasing network fault tolerance is introduced. To design such a framework, fault detection and recovery mechanisms for various fault levels including network nodes and communications between them have been used. The proposed management framework and protocols increase network’s fault tolerance capability in network nodes and in the communications between them. Also, the network lifetime increases three to five times more. On the one hand, it’s expected that the provision of network fault tolerance would decrease network’s lifetime and since it increases information exchange, it would increase energy consumption and cause reduced network life time, however the final results suggest a several-fold increase of network lifetime.     

Fault Tolerance and Energy Efficient Clustering Algorithm in Wireless Sensor Networks: FTEC

Wireless Personal Communications - The beacon order and Superframe order parameter values, as defined by the IEEE 802.15.4 standard specification, constrain the number of data packets that can be...     

一个基于网格资源超市的计算网格资源管理模型

在现有的基于经济模型的网格资源管理方法中,用户共享资源访问一般经由网格用户代理实现,而资源提供者将资源交给网格资源代理处理,网格用户代理通过网格资源经纪访问网格资源代理,获取共享资源信息并使用共享资源。这类方法制约了用户直接选择使用共享资源,也限制了用户共享资源的范围、延长了作业运行周期。文章给出的基于网格资源超市的计算网格资源管理模型、共享资源访问流程及网格资源管理分配策略,较好地解决了这几个问题。     

Resource Allocation for Real Time Services in LTE Networks: Resource Allocation Using Cooperative Game Theory and Virtual Token Mechanism

The LTE specifications provide QoS for multimedia services with fast connectivity, high mobility and security. However, 3GPP specifications have not defined scheduling algorithms to exploit the LTE characteristics to support real time services. In this article we propose a two level scheduling scheme composed by cooperative game theory, a virtual token mechanism, and the well known algorithms EXP-RULE and Modified-Largest Weighted Delay Firs (M-LWDF) in downlink system. By using cooperative game theory such as bankruptcy game and Shapley value, the proposed mechanism works by forming coalitions between flow classes to distribute the bandwidth fairly among all of them. Both algorithms EXP-RULE and M-LWDF have been modified to use a virtual token mechanism to improve their performance, giving priority to real time flows. By taking the arrival rate of packets into account, the proposed mechanism partially included in previous schedulers has been adapted to this work to increase remarkably the performance of the resource allocation for real time flows. The performance evaluation is conducted in terms of system throughput, Packet loss ratio, total cell spectral efficiency, delay and fairness index.     

Radio Resource Management in MIMO-OFDM- Mesh Networks: Issues and Approaches

We present a survey on the radio resource management issues in MIMO-OFDM-based infrastructure wireless mesh networks. The major components in radio resource management (i.e., scheduling and admission control) and related research issues are discussed. We review related work in the literature. We propose a game-theoretic model for admission control in IEEE 802.11n-based WMNs using the MIMO-OFDM technology. The proposed scheme uses Q-learning, which is a reinforcement learning algorithm, to gain knowledge on system performance. Then this knowledge is used to determine payoff for the game formulation to obtain the Nash equilibrium for the decision on admitting or rejecting a new connection at a mesh router.     

Automatic Uplink Resource Management in Mobile Cellular Networks: A Utility-Based Cooperative Power Control Strategy

This paper proposes a cooperative power control strategy for resource adaptation in mobile network to optimize user uplink transmission power. Our approach is based on a cooperative model using the economic concepts of utility function and the random graph theory. Based on the model, we develop a distributed power control algorithm that maximizes the utilities of all mobile users. Formulating this algorithm as a cooperative strategy, we show the uncertainty and existence of the power control approach with theory of random bipartite graph and utility function. A discussion to the existence of optimal solutions is given. Then a distributed power control scheme is proposed based on the optimal solutions. It is shown by way of simulation that by introducing utility function in the power control algorithm, there is a performance improvement in terms of the utilities that mobile users obtained. Numerical results are presented for the algorithm.     

Towards Reliable Configuration Management in Clouds: A Lightweight Consistency Validation Mechanism for Virtual Private Clouds

The virtual private cloud service currently lacks a real-time end-to-end consistency validation mechanism, which prevents tenants from receiving immediate feedback on their requests. Existing solutions consume excessive communication and computational resources in such large-scale cloud environments, and suffer from poor timeliness. To address these issues, we propose a lightweight consistency validation mechanism that includes real-time incremental validation and periodic full-scale validation. The former leverages message layer aggregation to enable tenants to swiftly determine the success of their requests on hosts with minimal communication overhead. The latter utilizes lightweight validation checksums to compare the expected and actual states of hosts locally, while efficiently managing the checksums of various host entries using inverted indexing. This approach enables us to efficiently validate the complete local configurations within the limited memory of hosts. In summary, our proposed mechanism achieves closed-loop implementation for new requests and ensures their long-term effectiveness.     

LPR: A CT and MR-Compatible Puncture Robot to Enhance Accuracy and Safety of Image-Guided Interventions

Image-guided percutaneous interventions are common procedures used for diagnosis or therapeutic purposes. The clinical demand for such interventions is growing since they are minimally invasive. To increase the quality of the operations and provide optimal accuracy and safety to patients, puncture robots may be very helpful. This paper presents a new robotic architecture designed to perform abdominal and thoracic punctures under computer tomography (CT) or MRI guidance. Innovations concerning the robotic architecture, materials, and energy sources are described. Segmentation and registration algorithms have been developed to localize the robot on images coming from CT or MRI devices, and a specific control loop is used to verify the movements and the positioning of the robot. The results of the initial experiments made under CT and MRI environments are presented.     

Small Cell Planning: Resource Management and Interference Mitigation Mechanisms in LTE HetNets

In an attempt to address the huge data demand of indoor mobile users and poor signal strength from outdoor base stations to indoor environments, opertaors have started deploying variety of small cells likes Femtos, picos and micro cells. In this work, we used Femtos as small cells. Femto cells are low-cost, low-power consuming cellular base stations which operate only in licensed spectrum and are designed for both outdoor and indoor communication. Although small cells can be used for enhancing network capacity and coverage, arbitrary deployment of large number of small cells can lead to increase in operators expenditure and may create severe interference issues for cell edge users. In this paper, we look into optimal placement of small cell solutions to improve data rates of users in LTE HetNets using Femtos. Besides, these solutions address the main concerns of interference and resource management by proposing mechanisms for optimal placement of Femtos (OptFP, MinNF), dynamic power control and bandwidth allocation in Femtos (SOPC) and dynamic offloading. We provide a comparison of placement solutions and the applicability of each proposal keeping the operators’ revenue in mind.

     

Correction to: G2A Communication Channel Modeling and Characterization Using Confocal Prolates

Wireless Personal Communications - The original publication contains the following errors:     

P2P下基于RSA密码机制和门限秘密共享的信誉管理方案

在P2P网络环境下,利用RSA密码机制和门限秘密共享进行信誉管理是一个非常有效的方案。利用秘密共享原理将信誉信息分成n个秘密份额,其中的任意t （t＜n ）个合法的秘密共享参与者均可以重新构造信誉信息。为了有效地防止网络中的恶意实体进行欺诈,方案中还配备了与每个秘密份额相对应的验证份额分发给相应的参与实体,任何非法参与实体冒称拥有秘密份额或者参与实体提供虚假的秘密份额,只有攻破了RSA密码才能不被识别出来,因此方案是安全有效的。     

Variable Frame Rate Transmission: A Review of Methodology and Application to Narrow-Band LPC Speech Coding

We review the variable frame rate (VFR) transmission methodology that we developed, implemented, and tested during the period 1973-1978 for efficiently transmitting LPC vocoder parameters extracted from the input speech at a fixed frame rate. In the VFR method, parameters are transmitted only when their values have changed sufficiently over the interval since their preceding transmission. We explored two distinct approaches to automatic implementation of the VFR method. The first approach bases the transmission decisions on comparisons of the parameter values of the present frame and the last transmitted frame. The second approach, which is based on a functional perceptual model of speech, compares the parameter values of all the frames that lie in the interval between the present frame and the last transmitted frame against a linear model of parameter variation over that interval. The application of VFR transmission to the design of narrow-band LPC speech coders with average bit rates of 2000-2400 bits/s is also considered. The transmission decisions are made separately for the three sets of LPC parameters, pitch, gain, and spectral parameters, using separate VFR schemes. A formal subjective spccch quality test of six selected LPC coders is described, and the results are presented and analyzed in detail. It is shown that a 2075 bit/s VFR coder produces speech quality equal to or better than that of a 5700 bit/s fixed frame rate coder.     

A Real-Time Monitoring and Intelligent Decisions-Making Platform for Enhanced Radio Resource Management in Wireless Cellular Systems

Congestion management in cellular networks is of prime importance for the mobile network operators of present and future generations. Nowadays cellular operators utilize improved planning techniques for enhanced capacity management, but on the other hand the number of mobile subscribers rapidly increases and additionally, new data-technologies for wireless access add extra traffic to the already overloaded networks, often causing serious problems to their performance. In this paper, we present a resource management system for increasing the efficiency of 2G and 2.5G cellular networks especially during overloading periods through the introduction of innovative extra elements. For validating the system's behavior, a set of trials have been performed focusing on alleviating both voice and data congestion problems. The results of these trials show important improvements on the network's capacity availability when the presented system intervenes.     

Correction to: Power and Resource Allocation in Wireless Communication Network

Wireless Personal Communications - Relying on the fact that, cascaded $$\alpha$$ – $$\mu$$ distribution provide simplified and excellent fitting to the measurement data compared to the other...     

Developments in the SL-10 Packet Switch: Resource, File, and Software Loading Management

The Northern Telecom SL-10 Packet Switching System is steadily enhanced to provide better access services for users. Equally important to them, but less visible, are enhancements to improve availability and increase throughput. To this end, intelligent peripheral devices, such as storage controllers and line servers, have been added to the Switch and new strategies, especially for software loading, have been devised. Such additions have had an impact on the software architecture. The Resource Subsystem now has to cope with a wider variety of devices, including intelligent peripheral devices. The File Subsystem has been generalized to accommodate files on different types of volumes, e.g., disks and tape cartridges. A whole new Subsystem has evolved to handle strategies for loading processors in parallel and to load intelligent peripherals. The SL-10 Packet Switch software architecture, with its process environment structured in Subsystems, has proven well suited to these requirements.     

Joint Channel and Power Allocation in Wireless Mesh Networks: A Game Theoretical Perspective

This paper addresses the throughput maximization problem in wireless mesh networks. For the case of cooperative access points, we present a negotiation-based throughput maximization algorithm which adjusts the operating channel and power level among access points automatically, from a gametheoretical perspective. We show that this algorithm converges to the optimal channel and power assignment which yields the maximum overall throughput with arbitrarily high probability. Moreover, we analyze the scenario where access points belong to different regulation entities and hence non-cooperative. The longterm behavior and corresponding performance are investigated and the analytical results are verified by simulations.     

Hazard-Free Self-Timed Design: Methodology and Application to Asynchronous Routing in an Heterogeneous Parallel Machine

The goal of this research is to enable the actual building of parallel machines. The example chosen in this paper is a heterogeneous parallel machine with an intrinsic asynchronous behavior. An asynchronous router fully supports such a logical asynchronism. However, every parallel processor would exhibit asynchronism similar enough to warrant the study of a general methodology. The main part of the paper deals with an original method that ensures a hazard-free self-timed design assuming the worst conditions for robustness. Hazards are classified under three types. On top of logic hazards that resort to implementation, equation hazards are eliminated by an optimal covering. A new variable labelled state-trajectory is proposed: its integrity guarantees immunity to function hazards. The method was fruitfully applied to the VLSI CMOS implementation of the above-mentioned router. Peculiar fully customized cells were designed. Circuit-measured performances as well as some machine inner-communication performances are presented.     

A Methodology for Variable Structure System Specification: Formalism,Framework, and Its Application to ATM-Based Network System

This paper presents a formalism-based methodology and its implemented environment which constitutes a sound framework for real-time systems development. The software and/or hardware systems developed in such a formal manner are wellstructured and maintainable. We first propose a set-theoretic VSSS (Variable Structure System Specification) formalism. This formalism is the core of the presented methodology which supports a means of formal specification for real-time systems. We then develop the environment, including VSSS language definition, a translator for the language, and supporting libraries for real-time execution. Finally, a demonstration of the methodology in development of a real-time event manager, a subsystem of an ATM-based communication system, shows the correctness and efficiency of the methodology.