Papers by Anna Lina Ruscelli
IEEE 802.11e HCCA reference scheduler guarantees Quality of Service only for Constant Bit Rate tr... more IEEE 802.11e HCCA reference scheduler guarantees Quality of Service only for Constant Bit Rate traffic streams, whereas its assignment of scheduling parameters (transmission time TXOP and polling period) is too rigid to serve Variable Bit Rate (VBR) traffic. This paper presents a new scheduling algorithm, Dynamic TXOP HCCA (DTH). Its scheduling scheme, integrated with the centralized scheduler, uses both a statistical estimation of needed transmission duration and a bandwidth reclaiming mechanism with the aim of improving the resource management and providing an instantaneous dynamic Transmission Opportunity (T XOP), tailored to multimedia applications with variable bit rate. Performance evaluation through simulation, confirmed by the scheduling analysis, shows that DTH is suitable to reduce the transmission queues length. This positively impacts on the delay and on packets drop rate experienced by VBR traffic streams.
Wireless Communications and Mobile Computing, Apr 18, 2019
The spreading diffusion of wireless devices and the crowded coexistence of multimedia application... more The spreading diffusion of wireless devices and the crowded coexistence of multimedia applications greedy of bandwidth and with strict requirements stress the service provisioning offered by wireless technologies. WiFi is a reference for wireless connectivity and it requires a continuous evolution of its mechanism in order to follow increasingly demanding service needs. In particular, despite the evolution of physical layer, some critical contexts, such as industrial networks, telemedicine, telerehabilitation, and virtual training, require further refined improvements in order to ensure the respect of strict real-time service requirements. In this paper an in-depth analysis of Dynamic TXOP HCCA (DTH) MAC enhanced centralized scheduler is illustrated and it is further refined introducing a new improvement, DTH with threshold. DTH and DTH with threshold can be integrated with preexisting centralized schedulers in order to improve their performances, without any overprovisioning that can negatively impact on the admission control feasibility test. Indeed, without modifying the centralized scheduler policy, they combine together the concepts of reclaiming transmission time and statistical estimation of the traffic profile in order to provide, at each polling, an instantaneous transmission time tailored to the variable traffic requirements, increasing, when necessary, the service data rate. These mechanisms can coexist with advanced physical layer-based solutions, providing the required service differentiation. Experimental results and theoretical analysis, based on elastic scheduler theory, show that they are effective especially in the case of Variable Bit Rate traffic streams in terms of transmission queues length, packets loss, delay, and throughput.
5G standardization is rapidly progressing and future vehicles will be connected, exchanging along... more 5G standardization is rapidly progressing and future vehicles will be connected, exchanging along the roads and on the Internet useful information for the safety of the road users. To target this goal, the Vehicle-to-Everything (V2X) standard starts to attract a lot of automobile industry and academic attention. The 5G Automotive Association categorizes a comprehensive list of connected vehicle applications, e.g. Advanced Driving Assistance (ADA) and Vulnerable Road User (VRU), that can have an implementation in the V2X environment. The expansion from Cloud to Edge Computing brings more processing power closer to the vehicles to guarantee the required latency and the need to have reduced network churn with continuous access to the Cloud. Edge Computing is addressing this paradigm shift by aiming to offer different services environment and cloud-computing capabilities within the roads infrastructure and the access network infrastructure in close proximity to vehicles and Road Side Units. This paper first overviews the V2X communication, in particular focusing on the ADA and VRU 5GAA use cases. Then it proposes a VRU warning system, which aims to provide an exchange information between the road users (e.g. pedestrian, cyclist, vehicles) about the presence of nearby entities in case of dangerous situation using commercial devices (i.e. smartphone) and standard compliant message. Finally, an experimental performance evaluation and comparison of the latency experienced by the client device considering firstly a Multi-Acces Edge Computing (MEC) based CAM Server and, then, a cloud-based CAM server are performed.
Quality of Service (QoS) provided by the IEEE 802.11e amendment and by the proposed HCF Controlle... more Quality of Service (QoS) provided by the IEEE 802.11e amendment and by the proposed HCF Controlled Channel Access (HCCA) reference scheduler is tailored for Constant Bit Rate traffic streams. Moreover the numerous alternative scheduling algorithms are not suitable to serve Variable Bit Rate (VBR) traffic streams with the required QoS and real-time guarantees. This paper presents Immediate Dynamic TXOP HCCA (IDTH), a new scheduling algorithm based on a bandwidth reclaiming mechanism suitable to cooperate with a HCCA real-time scheduler. IDTH recovers the portion of the transmission time unused by the scheduled stations to provide a further capacity for the next variable bit rate traffic streams. The transmission opportunity of the next scheduled station is assigned considering the available spare resources and the previously used ones. The scheduling analysis and the simulations results show that IDTH is suitable to reduce the delay experienced by VBR traffic streams, to efficiently deal with the variability of multimedia traffic and to avoid waste of resources.
International Journal of Ad Hoc and Ubiquitous Computing, 2016
IEEE 802.11e HCCA reference scheduler is based on fixed value parameters that do not adapt to tra... more IEEE 802.11e HCCA reference scheduler is based on fixed value parameters that do not adapt to traffic changes, thus quality of service (QoS) for multimedia applications is a challenge, especially in the case of variable bit rate (VBR) streams, that requires dynamic resource assignment. This paper is focused on immediate dynamic TXOP HCCA (IDTH) scheduling algorithm and its new evolution immediate dynamic TXOP HCCA plus (IDTH+). Their reclaiming mechanisms, refined by the monitoring of transmission duration, aim at overcoming the limits of fixed preallocation of resources by varying the stations transmission time and avoiding waste of resources. Simulations and theoretical analysis based on the imprecise computation model show that the integration of IDTH and IDTH+ can achieve improved network performance in terms of transmission queues length, mean access delay and packets drop rate, and to efficiently manage bursty traffic. Moreover, the performance improvements of IDTH+ with respect to IDTH are highlighted.
European Rail Traffic Management System (ERTMS) efficiently manages and schedules the trains guar... more European Rail Traffic Management System (ERTMS) efficiently manages and schedules the trains guaranteeing passengers safety and service constraints and maximizing railways capacity. The management system is responsible of the elaboration needed to control the trains circulation and to derive the necessary commands for trains and trackside actuators such as railroad switches. These operations need heavy computational resources and require an exchange of information between trains, trackside equipments and elaboration components. Currently the management system is hosted in the Central Control Rooms that centrally manage and supervise trains traffic of different geographical areas. This paper proposes a new paradigm about the execution of the ERTMS management activities taking advantage from cloud networks. It suggests to distribute among cloud resources the computational load due to the elaboration of the collected data and the derivation of required commands for trains and actuators. This can make possible a proactive approach to the trains management, suitable not only to consider the data sent by the trackside equipments, but also the information directly collected onboard of the train. Despite trackside data are considered by the management system, actually they are not integrated with onboard real-time data that are sent to the ground system for diagnosis purposes. These two sources of information can be jointly used to simulate in advance the train transit, deduce possible delays and anomalies and more efficiently manage the trains circulation.
Greenhouse effect due to CO2 emission is a global emergency issue affecting all human activities,... more Greenhouse effect due to CO2 emission is a global emergency issue affecting all human activities, including transportation systems. With the aim of reducing greenhouse gas emissions of the transport systems, the evolution of railway systems is toward environmental sustainability and energy efficiency. In this paper, a study about the use of energy harvesting to integrate the powering system of trains is presented. Currently available technologies are analyzed and photovoltaic systems are selected being technologically mature, since until now only big solar plants are considered as energy source for railways, and few studies have investigated solutions local to the trains. However, these studies date back to the early 2000s when photovoltaic technology was not sufficiently mature for this field of application. Taking advantage from the technology evolution the presented evaluation show by simulation that the electricity production can be increased until 400% with respect to the early 2000s. Furthermore, simulation results show that new power optimization solutions based on micro-inverters and on decoupling the PV modules of a string allow overcoming the limitation due to not optimal panel orientation on the train roof, train movement and shadows, increasing the production from 2 to 25%. The proposed approach can make the railway system more attractive for users sensitive to environmental issues and can promote intermodal connections with other green solutions for urban and local transport.
IEEE 802.11 based WLANs have became popular, but they can only provide best effort services and s... more IEEE 802.11 based WLANs have became popular, but they can only provide best effort services and so they are poorly suitable for multimedia applications. Recently IEEE 802.11e standard has been proposed to support quality of service. The new standard introduces a so-called Hybrid Coordination Function containing two medium access mechanisms: contention-based channel access and controlled channel access. In this paper we propose a novel framework to better support QoS guarantees for multimedia applications. It comprises QoS Manager, Admission Control, Enhanced Scheduler, Predictor and Feedback System. The scheduler adopted supports real-time applications, variable packet sizes and variable bit rate traffic streams. We show that this framework is suitable to be used by applications requesting Application Level Contracts which will be translated in Resource Level Contracts to the scheduler subsystem. The QoS manager component is able to dynamically manage available resources under different load conditions.
This paper presents a new scheduling algorithm, the Wireless Constant Bandwidth Server (W-CBS) fo... more This paper presents a new scheduling algorithm, the Wireless Constant Bandwidth Server (W-CBS) for the Access Points of an IEEE 802.11e wireless networks to support traffic streams with Quality of Service guarantees, in particular in the case of multimedia applications which present variable bit rate traffic. The performance of W-CBS is compared to that of the reference scheduler defined in 802.11e standard using the ns2 simulator. The results show that the W-CBS outperforms the reference scheduler with VBR traffic, in terms of resource utilization and maximum admitted flows.
Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, Aug 26, 2021
To increase operational efficiency, resilience and capacity of the railway system, the developmen... more To increase operational efficiency, resilience and capacity of the railway system, the development of modern railway traffic management system (TMS) has attracted more and more attention in recent years. To support the development and implementation of the next generation of TMS and related applications, advanced data collection, transmission and processing approaches, digitalised databases, and virtual validation platforms, etc., are required. In the context of the TMS development (addressed by Technology Demonstrator 2.9 of Shift2Rail Innovation Programme 2), this support is to be provided by a scalable, interoperable and standardised communication platform for internal and external communication between different subsystems, applications and clients. This paper outlines the approach of the ongoing OPTIMA project aimed to develop a communication platform demonstrator for railway TMS based on a novel Integration Layer (IL) and its various interfaces to entities including integration layer services, TMS service, rail business service, external services and operator workstations. Further detailed discussion in this paper relates to the approach to validating the communication platform demonstrator as a functional entity, and as a virtual testing environment to validate railway traffic management and other applications. The validation approach for the applications tested on the communication platform demonstrator is also presented. The results of future implementation of this validation approach will be used to assess the functionality of the communications platform demonstrator developed, and the initial TMS applications tested on it, and form an important step towards developing and implementing IL based communications platforms for future TMSs.
The design of a Wireless Sensor Network suitable to meet the applications requirements is particu... more The design of a Wireless Sensor Network suitable to meet the applications requirements is particularly relevant in environments where it is not possible to operate after the deployment, modifying the network to respect the desired behavior. This paper proposes a model to allow performance evaluation of the network before its deployment, helping its design and the choice of the right value of the network parameters. In particular our model is tailored for wireless sensor networks using the geographic routing. The model has been both numerically analyzed and simulated showing its ability to set such parameters to meet the requirements expressed in terms of established service levels.
Springer eBooks, 2007
This paper presents a novel approach to support Quality of Service for wireless multimedia applic... more This paper presents a novel approach to support Quality of Service for wireless multimedia applications in the context of 4G wireless systems. Adopting a Service Oriented Architecture, it is inspired to Open Wireless Architectures (OWA), building a suitable framework over the top of the heterogeneous wireless MACs. It lets to enhance the existing QoS support provided by standard MAC protocols and it uses the contract model to guarantee QoS, taking into account the applications requests. It negotiates dynamically Application Level Contracts which will be translated seamlessly in Resource Level Contracts for the underlying network services. It receives the feedback by underlying network services to adjust the scheduling algorithms and policies to provide soft guarantees. The framework comprises QoS Manager, Admission Control, Enhanced Scheduler, Predictor and Feedback System. In particular, the QoS manager component is a middleware between applications and lower network layers and it is able to dynamically manage available resources under different load conditions in a transparent manner to application level. .
The advent of softwarization implies a re-thinking of network design and management that positive... more The advent of softwarization implies a re-thinking of network design and management that positively impacts on service provisioning and maintenance efficiency. In particular, Software Defined Networking and Network Function Virtualization introduce abstraction techniques that are suitable for an easy and efficient deployment of service chain and for the use of general purpose hardware devices. The introduction of these paradigms in the railway domain is challenging due to its strict service and safety requirements, however it represents a promising approach enabling a disruptive improvement of the management systems and paving the way for next-generation railway control systems.This paper discusses and proposes the adoption of SDN/NFV (Software Defined Networks/Networks Function Virtualization) framework in railway control networks. In particular, some possible promising directions of investigation are drawn considering service orchestration and edge-based NFV services. Furthermore, two different applications are described focusing on SDN and NFV, respectively. An improved SDN failure recovery mechanism is proposed and evaluated showing the improvement in terms of recovery time. Instead, the introduction of configurable orchestration systems aiming to dynamically instantiate required services on Virtual Machines directly in the railway peripheral places by means of edge computing solutions for maintenance operations of peripheral assets is described and discussed.
Transportation research procedia, 2022
This paper first overviews the verticals supported by 5G technology in the 5G trial site of Bari ... more This paper first overviews the verticals supported by 5G technology in the 5G trial site of Bari and Matera. Such services will operate in the 3.6 - 3.8 GHz radio spectrum released by Italian Ministry of Economic Development for precommercial services. Special focus will be on use cases related to road safety. The issues and the possible solutions for implementing a pedestrian awareness service based on vehicle-to-pedestrian communication will be highlighted.
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Papers by Anna Lina Ruscelli