On the Minimization of Handover Decision Instability in Wireless Local Area Networks

This paper addresses handover decision instability which impacts negatively on both user perception and network performances. To this aim, a new technique called The HandOver Decision STAbility Technique (HODSTAT) is proposed for horizontal handover in Wireless Local Area Networks (WLAN) based on IEEE 802.11standard. HODSTAT is based on a hysteresis margin analysis that, combined with a utilitybased function, evaluates the need for the handover and determines if the handover is needed or avoided. Indeed, if a Mobile Terminal (MT) only transiently hands over to a better network, the gain from using this new network may be diminished by the handover overhead and short usage duration. The approach that we adopt throughout this article aims at reducing the minimum handover occurrence that leads to the interruption of network connectivity (this is due to the nature of handover in WLAN which is a break before make which causes additional delay and packet loss). To this end, MT rather performs a handover only if the connectivity of the current network is threatened or if the performance of a neighboring network is really better comparing the current one with a hysteresis margin. This hysteresis should make a tradeoff between handover occurrence and the necessity to change the current network of attachment. Our extensive simulation results show that our proposed algorithm outperforms other decision stability approaches for handover decision algorithm.Comment: 13 Pages, IJWM

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

An Autonomic Piloting Plane for the Handover Decision Optimization

International audienceWith the expansion and the diversification of current networks in terms of applications, technologies and services, the network control and management are becoming overly hard to manage manually even for skilled administrators. The autonomic computing and the knowledge plane are two promising initiatives proposed to cope with the ever-growth network complexity. In this article, we propose to use the piloting plane concept to grant autonomicity in current networks. This plane aims at optimizing existing applications by using elaborate algorithms fed by pertinent knowledge recovered from the knowledge plane. In our approach, we demonstrate that the knowledge and the piloting planes are complementary and both are required when implementing autonomic solutions. We illustrate our proposal by applying these concepts on the handover selection phase which is a key issue in the handover process for granting global mobility to users in heterogeneous environment. We also describe a first implementation of our handover piloting system. Results from preliminary tests in real environments scenario exhibit the effectiveness of our system

HODSTAT: A HandOver Decision STAbility Technique for minimizing instability in Wireless Local Area Networks

International audienceIn this paper a new technique called The HandOver Decision STAbility Technique (HODSTAT) is proposed for horizontal handover in Wireless Local Area Networks based on IEEE 802.11 standard. HODSTAT addresses the decision instability which impacts negatively on both user perception and network performances. HODSTAT is based on a hysteresis margin analysis that, combined with a utility-based function, evaluates the need for the handover and determines if the handover is needed or can be avoided. Indeed, if a Mobile Terminal (MT) only transiently hands over to a better network, the gain from using this new network may be diminished by the handover overhead and short usage duration. The approach that we adopt throughout this article aims at reducing with the minimum handover occurrence that leads to network connectivity cut which causes additional delay and packet loss. To this end, MT rather performs a handover only if the connectivity of the current network is threatened or if the performance of a neighboring network is really better comparing to the current one with a hysteresis margin. This hysteresis should make a tradeoff between handover occurrence and the necessity to change the current network of attachment. Through our extensive simulation results, we show that our proposed algorithm outperforms other decision stability approaches for handover decision algorithm

A Policy-based Orchestration Plane For The Autonomic Management Of Future Networks

International audienc

A knowledge plane for mobility management in Internet of things connected by radio

International audienc

Pyogenic Sacroiliitis in Children: Two Case Reports

Pyogenic sacroiliitis is rare and accounts for approximately 1-2% of osteoarticular infections in children. Considerable delay between presentation and diagnosis is recognized. Two cases of pyogenic sacroiliitis are described. The first case is a 28-month-old girl presented with acute onset of fever, pain in the left hip, and limpness. Computed tomography (CT), bone scans, and magnetic resonance imaging (MRI) of the pelvis showed characteristic findings of infectious sacroiliitis, and blood cultures were negatives. The second case is a 13-year-old girl presented with acute onset of fever, pain in the right hip, and buttock, with inability to walk. The diagnosis of pyogenic sacroiliitis was confirmed by bone scans, and CT of the pelvis and blood cultures have identified Proteus mirabilis. The two children recovered fully after 6 weeks of antimicrobial therapy. Pyogenic sacroiliitis is an uncommon disease in children. The key to successful management is early diagnosis in which CT, bone scans, and MRI findings play a crucial role. If the diagnosis is established promptly, most patients can be managed successfully with antimicrobial therapy

Practical Handover Optimization Solution Using Autonomic Agent-Based Piloting System

International audienceWith the multiplication of wireless communication networks and the increasing capabilities of the user devices equipped with multiple technology interfaces, being always connected tends to be a reality in the near future. In this article we propose to pilot the current weak handover algorithms using an autonomic agent-based piloting system. We specifically focus on the pre-execution handover process. The proposed system main contributions are to recover the useful information and compute it to obtain useful knowledge. This latter will be used for feeding a sophisticated handover decision algorithm in order to pick the most appropriate access network. We have developed a real testbed to evaluate and validate our solution unlike most proposed works analyzed only by simulations and thus avoid practical problems encountered in real environment. Above this real platform we performed an experimentation in 802.11 wireless networks that shows promising results

Digital Biomarker–Based Studies: Scoping Review of Systematic Reviews

BackgroundSensors and digital devices have revolutionized the measurement, collection, and storage of behavioral and physiological data, leading to the new term digital biomarkers. ObjectiveThis study aimed to investigate the scope of clinical evidence covered by systematic reviews (SRs) of randomized controlled trials involving digital biomarkers. MethodsThis scoping review was organized using the PRISMA-ScR (Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews) guidelines. With the search limited to English publications, full-text SRs of digital biomarkers included randomized controlled trials that involved a human population and reported changes in participants’ health status. PubMed and the Cochrane Library were searched with time frames limited to 2019 and 2020. The World Health Organization’s classification systems for diseases (International Classification of Diseases, Eleventh Revision), health interventions (International Classification of Health Interventions), and bodily functions (International Classification of Functioning, Disability, and Health [ICF]) were used to classify populations, interventions, and outcomes, respectively. ResultsA total of 31 SRs met the inclusion criteria. The majority of SRs studied patients with circulatory system diseases (19/31, 61%) and respiratory system diseases (9/31, 29%). Most of the prevalent interventions focused on physical activity behavior (16/31, 52%) and conversion of cardiac rhythm (4/31, 13%). Looking after one’s health (physical activity; 15/31, 48%), walking (12/31, 39%), heart rhythm functions (8/31, 26%), and mortality (7/31, 23%) were the most commonly reported outcomes. In total, 16 physiological and behavioral data groups were identified using the ICF tool, such as looking after one’s health (physical activity; 14/31, 45%), walking (11/31, 36%), heart rhythm (7/31, 23%), and weight maintenance functions (7/31, 23%). Various digital devices were also studied to collect these data in the included reviews, such as smart glasses, smartwatches, smart bracelets, smart shoes, and smart socks for measuring heart functions, gait pattern functions, and temperature. A substantial number (24/31, 77%) of digital biomarkers were used as interventions. Moreover, wearables (22/31, 71%) were the most common types of digital devices. Position sensors (21/31, 68%) and heart rate sensors and pulse rate sensors (12/31, 39%) were the most prevalent types of sensors used to acquire behavioral and physiological data in the SRs. ConclusionsIn recent years, the clinical evidence concerning digital biomarkers has been systematically reviewed in a wide range of study populations, interventions, digital devices, and sensor technologies, with the dominance of physical activity and cardiac monitors. We used the World Health Organization’s ICF tool for classifying behavioral and physiological data, which seemed to be an applicable tool to categorize the broad scope of digital biomarkers identified in this review. To understand the clinical value of digital biomarkers, the strength and quality of the evidence on their health consequences need to be systematically evaluated