Wide Area Network Access Research Articles

$FREE$ —Fine-Grained Scheduling for Reliable and Energy-Efficient Data Collection in LoRaWAN

LoRaWAN promises to provide wide-area network access to low-cost devices that can operate for up to ten years on a single 1000-mAh battery. This makes LoRaWAN particularly suited for the data collection applications (e.g., monitoring applications), where device lifetime is a key performance metric. However, when supporting a large number of devices, LoRaWAN suffers from a scalability issue due to the high collision probability of its Aloha-based MAC layer. The performance worsens further when using acknowledged transmissions due to the duty-cycle restriction at the gateway. For this, we propose FREE , a fine-grained scheduling scheme for reliable and energy-efficient data collection in LoRaWAN. FREE takes advantage of applications that do not have hard delay requirements on data delivery by supporting the synchronized bulk data transmission. This means data are buffered for transmission in scheduled time slots instead of transmitted straight away. FREE allocates spreading factors, transmission powers, frequency channels, time slots, and schedules slots in frames for LoRaWAN end-devices. As a result, FREE overcomes the scalability problem of LoRaWAN by eliminating collisions and grouping acknowledgments. We evaluate the performance of FREE versus different legacy LoRaWAN configurations. The numerical results show that FREE scales well and achieves almost 100% data delivery and the device lifetime is estimated over ten years independent of traffic type and network size. In comparison to poor scalability, low data delivery and device lifetime of fewer than two years for acknowledged data traffic in the standard LoRaWAN configurations.

Design, implementation and analysis of cognitive radio enabled intelligent WBAN gateway for cost-efficient remote health monitoring

In this paper, we design and implement an intelligent gateway for Wireless Body Area Network (WBAN) that seeks opportunistic access of licensed Primary User (PU) channels using Cognitive Radio (CR) to facilitate spectral-efficient, cost-efficient and reliable Non-Real Time (NRT) backhaul transmission of WBAN data for ubiquitous healthcare monitoring. The controller is termed herein as BodyCog-BNC. We develop and implement a cross-layer based modified protocol stack at the BodyCog-BNC, comprising of BodyCog-BNC Management Entity (BME) and BodyCog-BNC CR Medium Access Control (BCR-MAC) units, to exploit cross layer message passing to support the novel idea of spectrum agility. A spectral agile BodyCog-BNC is capable of intelligently switching to conventional licensed Wide-Area Access Network (WAN) technology in case of lack of proper PU channels or occurrence of successive handoffs in multiple PU channels. Furthermore, the protocol stack facilitates session management and energy-efficient backhaul CR transmission over a PU channel employing a proposed Inter-Sensing Time Optimization (ISTO) algorithm. ISTO leverages on convex optimization to select the optimum inter-sensing time for a PU channel to maximize the energy-efficiency within a PU interference constraint under sensing uncertainties. Closed form analytical expressions are also derived to estimate the average consumed energy, switching probability, switching time and the cost-efficiency of BodyCog-BNC. Exhaustive performance analysis shows that the BodyCog-BNC (WBAN gateway), provides a cost-efficient solution for different healthcare applications under varied operating conditions and CR cost regimes. Finally, through a prototype implementation and proof of concept we validate the ability of BodyCog-BNC in enabling NRT remote healthcare monitoring.

전력수용가포털을 위한 구내 통신 및 컴퓨터 네트워크 용량 설계

Consumer Portal is defined as combination of hardware and software that enables two-way communication between energy service provider(ESP, like KEPCO) and equipment within the consumer`s premises. The portal provides both a physical link(between wires, radio waves, and other media) and a logical link(translating among language-like codes and etiquette-like protocols) between in-building and wide-area access networks. Thus, the consumer portal is an important, open public shared infrastructure in the future vision of energy services. In this paper, we describe a new methodology for local communication and computer network capacity design of consumer portal, and also presents capacity calculation method using a network system limitation factors. By the approach, we can check into the limitations of existing methods, and propose an improved data processing algorithm that can expand the maximum number of the networked end-use devices up to times. For validation, we applies the proposed methode to our real system design. Our contribution will help electrical power information network design.

PsXML: 서비스 중심적 개방형 아키텍처를 가지는 수용가포털을 위한 XML 기반의 표준화

고전력수용가포털(Consumer Portal)은 소비자의 다양한 장치들과 광역 네트워크, 그리고 에너지서비스사업자 (ESP: 한전 등)의 서비스 애플리케이션 플랫폼을 연결하는 물리적 링크이자 논리적 결합으로, 전력서비스 체계에서 소비자-공급자 간 정보교환과 서비스 거래를 담당하는 양방향 통신의 핵심 인프라로서 포털이다.BR 전력수용가포털(Consumrr Portal)의 성공적인 설계와 개발을 위해서는 효율성, 경제성, 확장성을 고려한 서비스 중심적 표준화 전략이 중요하게 고려되어야 한다. 본 논문에서는 전력수용가포털 설계에 필요한 XML기반의 표준화 안을 psXML(Power System XML)로 제안하고 이를 설계, 구현하여 실제 구축 중인 시스템에 적용하였다. 이는 네트워크 및 프로세서 부담을 최소화할 수 있는 수용가포털을 위한 개방형 표준을 구현한 것이다.

Quality of Service Measurements over an Optical GMPLS Wide Area Access Network

The introduction of intelligence for management and control of optical networks based on internet protocol and the quality of service (QoS) are key issues for the evolution of the next generation network. In this paper the authors report experimental results on QoS measurements related to different real time multimedia services in an optical network based on a ring configuration obtained by means of the fibers contained in an installed cable between Rome and Pomezia, core routers with optical Gigabit Ethernet interfaces and configured with differentiated service over multi-protocol label switching architecture.

A framework of handoffs in wireless overlay networks based on mobile IPv6

Although there are various wireless access network technologies with different characteristics and performance level have been developed, no single network that can satisfy the anytime, anywhere, and any service wireless access needs of mobile users. A truly seamless mobile environment can only be realized by considering vertical and horizontal handoffs together. With the advantages of Mobile IPv6, a more comprehensive and integrated framework of heterogeneous networks can be developed. In this paper, we discuss the issues related to handoffs including horizontal and vertical handoffs. We present a scheme for integrating wireless local area network and wide area access networks, and propose a micromobility management method called HiMIPv6+. We also propose a QoS-based (quality-of-service-based) vertical handoff scheme and algorithm that consider wireless network transport capacity and user service requirement. Our prototype evaluations and the simulations show that our framework performs as expected.

A GRASP algorithm with RNN based local search for designing a WAN access network

Abstract The Greedy Randomized Adaptive Search Procedure (GRASP) is a well-known metaheuristic for combinatorial optimization. In this work, we introduce a GRASP for designing the access network topology of a Wide Area Network (WAN). This problem is NP-hard, and can modeled as a variant of the Steiner Problem in Graphs. The proposed GRASP employs a Random Neural Network (RNN) model in the local search phase, in order to improve the solutions delivered by the construction phase, based on a randomized version of the Takahashi-Matsuyama algorithm. Experimental results were obtained on 155 problem instances of different topological characteristics, generated using the problem classes in the SteinLib repository, and with known lower bounds for their optima. The algorithm obtained good results, with low average gaps with respect to the lower bounds in most of the problem classes, and attaining the optimum in 40 cases (more than 25% of the problem set).

Super-dense WDM transmission of spectrum-sliced incoherent light for wide-area access network

This paper presents a detailed study on superdense wavelength-division multiplexing (WDM) transmission of spectrum-sliced incoherent light used for a wide-area access network. The transmission performance possible with this approach is evaluated numerically with regard to the following items: the transmission limit due to the chromatic dispersion, optimized signal-to-noise ratio design for the optical spectral width taking into account the adjacent-channel crosstalk, and the nonlinear effect generated by four-wave mixing at around the zero-dispersion wavelength. Superdense WDM transmission is also performed experimentally using 25-GHz channel-spaced, 15-GHz wide, up-to 156-Mb/s signals through up to 120 km of dispersion-shifted fiber.

Remote handling of TEXTOR diagnostics using CORBA as communication architecture

At the Forschungszentrum Jülich, an upgrade of the existing distributed system for data acquisition (DAS) at the fusion experiment TEXTOR94 is under development. DAS is currently restricted to VAX/VMS and DECNET based communications, but it is planned to add UNIX based systems, and to open the local network for an improved wide area network access for remote operations. Therefore, the DAS system is to be equipped with a suitable client/server interface, which is able to cope with the various computer platforms and operating systems involved. For this purpose, the common object request broker architecture (CORBA) will be used. CORBA is an object oriented, standardized architecture for distributed systems, which provides a high degree of modularity in software design and allows for flexible implementations. It is to act as a connecting link between the existing system and new extensions. In order to provide the desired client/server functionality for the data acquisition tasks, the components of the system (diagnostic, database, etc.) are modelled by CORBA interfaces. Processes for diagnostic control and data readout in the existing OpenVMS systems are aimed at to be accessible by CORBA server implementations. The corresponding client implementations will be developed for the operating system platforms most frequently used at TEXTOR94. Communication between clients and server will be based on TCP/IP and are to be managed by CORBA. By this standardized way, remote control of diagnostic instrumentation becomes possible in a multiplatform computer and wide area network environment. At a later stage it is intended to integrate the system into a ‘virtual control room’ environment, which should enable the participation of cooperating institutions in the full experimental program of TEXTOR94.

Building a virtual machine-room — a focal point in metacomputing

Computing resources which are transparently available to the user via networked environments are commonly called a metacomputer. In this sense, a metacomputer is a network of heterogeneous, computational resources linked by software in such a way that they can be used as easily as a single computational unit. During the last few years our work has been concentrated on developing methods and tools to provide a transparent and vendor independent hardware management system to the users. Solving this problem up to a high abstraction level will bring the idea of metacomputing a large step closer to its fruition. After reviewing the metacomputing approaches in Europe and the States, we will break down the task force into almost independent units. One of these, the resource access and allocation problem, the project Computing Center Software was focused on. This paper takes a closer look at CCS. Its underlying model which uses abstract views for specifying system components and the general purpose Resource Description Language will be sketched. We will explain how it is possible to support Wide-Area Network access and unstable connection lines. Afterwards, we will present the system and vendor independent batch processing facility usable for arbitrary programming environments. On-going activities and an enhancement of the CCS methodology to solve a core problem in wide-area metacomputing will conclude this paper.