Towards energy-autonomous wake-up receiver using visible light communication

The use of Visible Light Communication (VLC) in wake-up communication systems is a potential energy-efficient and low-cost solution for wireless communication of consumer electronics. In this paper, we go one step further and propose the use of visible light both for wake-up communication and energy harvesting purposes, with the final objective of an energy-autonomous wake-up receiver module. We first present the details and the design criteria of this novel system. We then present the results of evaluation of design criteria such as solar panel and capacitor type choices. To evaluate the performance of the developed wake-up system with energy-autonomous receiver system, we perform realistic indoor scenario tests, analyzing the effect of varying distances, angles, and light intensities as well as the effect of presence of interfering lights.Peer ReviewedPostprint (author's final draft

Evolutionary 4G/5G network architecture assisted efficient handover signaling

Future wireless networks are expected to be ultra-dense and heterogeneous not just in terms of the number and type of base stations but also in terms of the number of users and the application types they access. Such a network architecture will require mobility management mechanisms that adapt rapidly to these highly dynamic network characteristics. In particular, the optimality of the handover signaling within these future network architectures will be extremely critical given their density and heterogeneity. In this paper, the optimality is relevant for both the total amount of signaling created and the total delay per handover process. In this paper, we first present a novel and optimized message mapping and signaling mechanism for the handover preparation and failure phases. We also develop a novel handover failure aware preparation signaling methodology, which accounts for the possibility of a handover failure and grants additional enhancements to the handover preparation and failure signaling phases. Through the analytical framework provided in this paper, we conduct studies to quantify the performance gains promised by the proposed mechanisms. These studies cover myriad handover scenarios as identified by 3GPP and use the statistics from cellular network operators and vendors. We then develop the idea and analytical framework for network wide analysis, in which the network wide processing cost and network occupation time for various handover failure rates are computed. Finally, we propose an evolutionary network architecture that facilitates the proposed signaling mechanism as well as assists operators in maintaining a manageable capital expenditure. It combines the current day and 3GPP proposed 5G network architecture with the software-defined networking approach. As a result, we argue that the proposed mechanisms are viable and outperform the legacy handover signaling mechanisms in terms of latency incurred, total network occupation time, number of messages generated, and total bytes transferred.Peer ReviewedPostprint (author's final draft

Improved handover signaling for 5G networks

© 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.Mobility management is a critical component for any new wireless standard to be ubiquitous. While 4G-LTE and prior wireless standards utilized vendor specific hardware and software on which mobility management (MM) functionality was implemented, recent 5G architecture releases by 3GPP indicate a complete departure from the same. 3GPP in release 14 and the upcoming release 15 has stressed upon the utilization of Software Defined Networking (SDN) and Network Function Virtualization (NFV) as the drivers of 5G technology. Consequently, new challenges related to MM and specifically handover management will be encountered owing to the inter-working setup between the 5G Next-Gen Core (NGC) and the Evolved Packet System (EPS) core. In this paper, we exploit the SDN to enhance the signaling of the HO methods proposed by 3GPP. Although the proposed approach can be applied to any HO method, in this paper we specifically evaluate the scenario wherein a dedicated interface between the Mobility Management Entity (MME) in the EPC and the Access and Mobility management Function (AMF) in the 5G NGC, i.e., N26 as specified by 3GPP, is non-existent. Such a scenario is reasonable during the initial deployment phases of 5G networks. We show that the proposed mechanism is efficient as compared to the 3GPP handover strategy in terms of latency, transmission and processing costs.Peer ReviewedPostprint (author's final draft

Enhanced handover signaling through integrated MME-SDN controller solution

© 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.The future wireless networks are expected to be extremely dense and heterogeneous, with the users experiencing multi-connectivity through the multiple available radio access technologies (RATs). These prevalent characteristics, along with the strict QoS requirements, renders the handover (HO) process optimization as a critical objective for future networks. Along side the evolving network characteristics and methodologies, an evolving network architecture needs to be considered as well. Such evolution should not only facilitate HO process enhancement, i.e., reduction in HO delay and signaling, but it should also allow for a smooth transition from current to future wireless networks. Hence, in this work we firstly present an evolutionary core network entity called the Integrated MME-SDN Controller and the associated network architecture. The proposed architecture provides a migratory path for the existing 3GPP cellular architectures towards the 5G networks. Next, we discuss the benefits and challenges of such an architectural approach, with one of the benefits being a manageable CAPEX for the network operators through its transitional nature. Subsequently, utilizing the aforementioned proposed architecture, we present the handover process enhancement for the current 3GPP defined HO processes. We quantify the improvements achieved in terms of latency, transmission and processing cost for the different 3GPP HO processes. We also show that the proposed HO mechanism leads to a significant reduction in latency and signaling for certain types of HOs which, as a consequence, will critically benefit any dense and heterogeneous wireless system, such as 5G.Peer ReviewedPostprint (author's final draft

Active queue management as quality of service enabler for 5G networks

© 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.5G is envisioned as the key technology for guaranteeing low-latency wireless services. Packets will be marked with QoS Flow Indicators (QFI) for different forwarding treatment. 3GPP defines the end-to-end delay limits, but leaves the QoS provisioning methods as implementation dependent. Different services with different constraints will inevitably share queues at some network entity. On the one hand, maintaining the shared queues uncongested will guarantee a rapid packet delivery to the subsequent entity. A brief sojourn time is indispensable for an on time low-latency priority traffic delivery. On the other hand, if shared queues are maintained undersized, throughput will be squandered. In this paper, we propose the use of AQM techniques in 5G networks to guarantee delay limits of QoS flows. Through the evaluation of realistic delay-sensitive and background traffic, we compare different possible solutions. We show that AQM mechanisms together with limited queues, maintain the system uncongested, which reduces drastically the delay, while effectively achieving the maximum possible throughput.Peer ReviewedPostprint (author's final draft

Thrombosis with Behçet’s disease should be evaluated different conditions

No Abstract

Evaluation of the angulation of the nasal septum deviation as an anatomical variation for increased frequency of antral pseudocyst: A cone beam computed tomography study

Background: To determine whether degree of the nasal septum deviation (NSD) can affect the frequency of antral pseudocyst (AP) formation by cone beam computed tomography (CBCT).  Materials and methods: This retrospective study was included 466 CBCT images. The NSD were categorized into four groups according to the degree: Control group (no NSD, 0°-2°), Group A (2°-9°), Group B (9°-15°), and Group C (≥15°). The predictor variables were demographic factors (patient’s age and gender) and anatomic factors (different degrees of nasal septum angulation). The outcome variable was presence of AP. Results: Of the 466 cases, 242 (51.9%) had no NSD, 66 (14.2%) had an angle of 2°-9°, 111 (23.8%) had an angle of 9°-15°, and 47 (10.1%) had an angle of over 15°. The prevalence of AP was 2.04 (95% CI, 1.37 to 3.03; p=0.001) times higher in the presence of NSD. Significant increases in presence of AP occurred with NSD in Group A (2.37 times higher; P=.003) and Group B (2.07 times higher; P=.003) compared to control by univariate analysis. Conclusions: Although there is no sufficient evidence to suggest that NSD is a definitive etiological factor for AP development, our findings indicated that NSD increased the risk of AP formation

IEEE 802.11-Enabled Wake-Up Radio: use cases and applications

IEEE 802.11 is one of the most commonly used radio access technologies, being present in almost all handheld devices with networking capabilities. However, its energy-hungry communication modes are a challenge for the increased battery lifetime of such devices and are an obstacle for its use in battery-constrained devices such as the ones defined by many Internet of Things applications. Wake-up Radio (WuR) systems have appeared as a solution for increasing the energy efficiency of communication technologies by employing a secondary low-power radio interface, which is always in the active state and switches the primary transceiver (used for main data communication) from the energy-saving to the active operation mode. The high market penetration of IEEE 802.11 technology, together with the benefits that WuR systems can bring to this widespread technology, motivates this article’s focus on IEEE 802.11-basedWuR solutions. More specifically, we elaborate on the feasibility of such IEEE 802.11-based WuR solutions, and introduce the latest standardization efforts in this IEEE 802.11-based WuR domain, IEEE 802.11ba, which is a forthcoming IEEE 802.11 amendment, discussing its main features and potential use cases. As a use case consisting of green Wi-Fi application, we provide a proof-of-concept smart plug system implemented by a WuR that is activated remotely using IEEE 802.11 devices, evaluate its monetary and energy savings, and compare it with commercially available smart plug solutions. Finally, we discuss novel applications beyond the wake-up functionality that IEEE 802.11-enabled WuR devices can offer using a secondary radio, as well as applications that have not yet been considered by IEEE 802.11ba. As a result, we argue that the IEEE 802.11-based WuR solution will support a wide range of devices and deployments, for both low-rate and low-power communications, as well as high-rate transmissions.Postprint (author's final draft

Pharmacokinetics of orally administered tetrahydrobiopterin in patients with phenylalanine hydroxylase deficiency

Summary: The oral loading test with tetrahydrobiopterin (BH4) is used to discriminate between variants of hyperphenylalaninaemia and to detect BH4-responsive patients. The outcome of the loading test depends on the genotype, dosage of BH4, and BH4 pharmacokinetics. A total of 71 patients with hyperphenylalaninaemia (mild to classic) were challenged with BH4 (20 mg/kg) according to different protocols (1 × 20 mg or 2 × 20 mg) and blood BH4 concentrations were measured in dried blood spots at different time points (T0, T2, T4, T8, T12, T24, T32 and T48 h). Maximal BH4 concentrations (median 22.69 nmol/g Hb) were measured 4 h after BH4 administration in 63 out of 71 patients. Eight patients presented with maximal BH4 concentrations ∼44% higher at 8 h than at 4 h. After 24 h, BH4 blood concentrations dropped to 11% of maximal values. This profile was similar using different protocols. The following pharmacokinetic parameters were calculated for BH4 in blood: t max = 4 h, AUC (T0−32) = 370 nmol × h/g Hb, and t 1/2 for absorption (1.1 h), distribution (2.5 h), and elimination (46.0 h) phases. Maximal BH4 blood concentrations were not significantly lower in non-responders and there was no correlation between blood concentrations and responsiveness. Of mild PKU patients, 97% responded to BH4 administration, while one was found to be a non-responder. Only 10/19 patients (53%) with Phe concentrations of 600-1200 μmol/L responded to BH4 administration, and of the patients with the severe classical phenotype (blood Phe > 1200 μmol/L) only 4 out of 17 patient responded. An additional 36 patients with mild hyperphenylalaninaemia (HPA) who underwent the combined loading test with Phe+BH4 were all responders. Slow responders and non-responders were found in all groups of HP