Hierarchical routing protocols for wireless sensor network: a compressive survey

Wireless Sensor Networks (WSNs) are one of the key enabling technologies for the Internet of Things (IoT). WSNs play a major role in data communications in applications such as home, health care, environmental monitoring, smart grids, and transportation. WSNs are used in IoT applications and should be secured and energy efficient in order to provide highly reliable data communications. Because of the constraints of energy, memory and computational power of the WSN nodes, clustering algorithms are considered as energy efficient approaches for resource-constrained WSNs. In this paper, we present a survey of the state-of-the-art routing techniques in WSNs. We first present the most relevant previous work in routing protocols surveys then highlight our contribution. Next, we outline the background, robustness criteria, and constraints of WSNs. This is followed by a survey of different WSN routing techniques. Routing techniques are generally classified as flat, hierarchical, and location-based routing. This survey focuses on the deep analysis of WSN hierarchical routing protocols. We further classify hierarchical protocols based on their routing techniques. We carefully choose the most relevant state-of-the-art protocols in order to compare and highlight the advantages, disadvantage and performance issues of each routing technique. Finally, we conclude this survey by presenting a comprehensive survey of the recent improvements of Low-Energy Adaptive Clustering Hierarchy (LEACH) routing protocols and a comparison of the different versions presented in the literature

Canagliflozin and renal outcomes in type 2 diabetes and nephropathy

BACKGROUND Type 2 diabetes mellitus is the leading cause of kidney failure worldwide, but few effective long-term treatments are available. In cardiovascular trials of inhibitors of sodium–glucose cotransporter 2 (SGLT2), exploratory results have suggested that such drugs may improve renal outcomes in patients with type 2 diabetes. METHODS In this double-blind, randomized trial, we assigned patients with type 2 diabetes and albuminuric chronic kidney disease to receive canagliflozin, an oral SGLT2 inhibitor, at a dose of 100 mg daily or placebo. All the patients had an estimated glomerular filtration rate (GFR) of 30 to <90 ml per minute per 1.73 m2 of body-surface area and albuminuria (ratio of albumin [mg] to creatinine [g], >300 to 5000) and were treated with renin–angiotensin system blockade. The primary outcome was a composite of end-stage kidney disease (dialysis, transplantation, or a sustained estimated GFR of <15 ml per minute per 1.73 m2), a doubling of the serum creatinine level, or death from renal or cardiovascular causes. Prespecified secondary outcomes were tested hierarchically. RESULTS The trial was stopped early after a planned interim analysis on the recommendation of the data and safety monitoring committee. At that time, 4401 patients had undergone randomization, with a median follow-up of 2.62 years. The relative risk of the primary outcome was 30% lower in the canagliflozin group than in the placebo group, with event rates of 43.2 and 61.2 per 1000 patient-years, respectively (hazard ratio, 0.70; 95% confidence interval [CI], 0.59 to 0.82; P=0.00001). The relative risk of the renal-specific composite of end-stage kidney disease, a doubling of the creatinine level, or death from renal causes was lower by 34% (hazard ratio, 0.66; 95% CI, 0.53 to 0.81; P<0.001), and the relative risk of end-stage kidney disease was lower by 32% (hazard ratio, 0.68; 95% CI, 0.54 to 0.86; P=0.002). The canagliflozin group also had a lower risk of cardiovascular death, myocardial infarction, or stroke (hazard ratio, 0.80; 95% CI, 0.67 to 0.95; P=0.01) and hospitalization for heart failure (hazard ratio, 0.61; 95% CI, 0.47 to 0.80; P<0.001). There were no significant differences in rates of amputation or fracture. CONCLUSIONS In patients with type 2 diabetes and kidney disease, the risk of kidney failure and cardiovascular events was lower in the canagliflozin group than in the placebo group at a median follow-up of 2.62 years

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Summary Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030

Energy Efficiency in Wireless Access Networks: Measurements, Models and Algorithms

Wireless Telecommunication networks have become fundamental to daily activities. Today, people have access to at least one type of wireless telecommunication network. In this context, optimizing the energy consumption of wireless telecommunications infrastructure has become a new challenge for the research community, governments and industries in order to reduce CO2 emission and operational energy costs. This thesis investigates the power consumption of indoor/outdoor Wireless Access Devices (WADs, specifically WiFi and WiMAX access points) and provides novel techniques for improving the energy efficiency of wireless access networks. Our approach focuses on monitoring and analyzing the power consumption of WADs using real-testbed and experimental measurements in order to understand the fundamental limits and trade-offs involved. This, in turn, will be used to propose efficient techniques to reduce power consumption and to maximize the energy efficiency of wireless access networks. We introduce energino a novel hardware and software solution for real-time energy consumption monitoring in wireless networks. We also propose an experimentally-driven approach to (i) characterize typical WADs from a power consumption standpoint, (ii) develop simple and accurate power consumption models and metrics for such WADs, and (iii) design techniques to tune the power consumption of a wireless infrastructure to the actual network conditions in terms of both users density and traffic patterns. Our measurements from several real-life deployments show that (a) the power consumption of such WADs exhibits a linear dependence on the traffic until a saturation point is reached and (b) the developed techniques can deliver significant energy savings with minimal degradation in terms of the quality of service provided

On Efficient Airtime-based Fair Link Scheduling in IEEE 802.11-based Wireless Networks

In this paper, we present the Airtime Deficit Round Robin (ADRR), a novel scheduling algorithm for IEEE 802.11-based wireless networks. The ADRR mechanism enhances the Deficit Round Robin scheduling discipline by taking into account the channel quality experienced by the transmitting node. The devised algorithm addresses the IEEE 802.11 performance anomaly, preventing a node which experiences poor channel conditions from monopolizing the wireless medium, lowering the performance of the whole system. The proposed approach combines link scheduling with measurable routing metrics. Simulation analyses have shown that the proposed scheme can achieve performance isolation among links characterized by heterogeneous channel conditions. A real prototype has been implemented and evaluated over a small scale testbed confirming the simulation results

Empirical Comparison of the Energy Consumption of Cellular Internet of Things Technologies

Today we are living in a society where an ever increasing number of devices or things are being connected to the Internet. Many of these devices are battery powered with the long term success of the business case justifying the deployment of these devices, dependent upon the ability of these devices to operate autonomously for extended periods without intervention to replace batteries. Utility companies delivering water and gas are seeking 10 year plus lifetimes from devices without a truck roll to replace batteries. The current industry understanding of the 5G technologies, NB-IoT and eMTC, is NB-IoT offers lower power consumption but there is little evidence for that belief. This paper uses standard load models to systematically investigate the energy demands of the two different radio access technologies under realistic usage patterns. The paper also investigates some key factors influencing energy consumption and whether a device could operate from an ideal 5 Wh battery for 10 years. In contributing to the field of knowledge in this area, we set out to compare 3GPP IoT radio access technologies using techniques aligned with existing 3GPP energy consumption evaluation methodologies. In adopting that approach, contrary to established industry opinions and messaging, we found when operating as an eMTC device, our radio module consumes less power than when it was operating as an NB-IoT device. Irrespective of it&#x2019;s operating mode, our radio module was unable to achieve a 10 year battery life from an ideal 5 Wh battery using a typical IoT traffic model. Most interestingly, we observed minimal change in energy consumption whether the payload size was 1 byte or 1400 bytes

Mice over mesh: HTTP measurements over a WiFi-based wireless mesh network

Wireless mesh networks are emerging as a promising access network architecture. In this work, we report on an extensive measurement campaign performed over an experimental WiFi-based mesh network, deployed in an office building environment. The measurements are focused on the performance of HTTP traffic. Results demonstrate the existence of an unfairness issue, whereby longer sessions achieve better performance than shorter ones. This is known to be potentially harmful in terms of mean session delay and user-perceived quality of service. Potential countermeasures are presented and discussed

An MDP-based energy efficient and delay aware handover algorithm

Islam, N ORCiD: 0000-0002-5469-8104This paper presents a novel energy efficient and delay aware handover decision policy based on Markov decision process (MDP) for a two-tier (macro-femto) wireless network. We propose a novel reward function and formulate a novel transition probability matrix to be used in MDP in order to take optimal handover decision. Simulation results reveal that, compared to other competitive handover policies, the proposed policy can significantly reduce the power consumption as well as handover delay at the mobile terminals

Energino: Energy Saving Tips for Your Wireless Network

The energy wasted in wireless networks is a serious concern and the main challenge lies in determining when and where the energy is wasted. In this demo, we present Energino, an energy measurement and control system designed to deliver high performance while remaining a cheap solution

Energy efficient and delay aware ternary-state transceivers for aerial base stations

In recent times, Aerial Base Stations(AeBSs) are being investigated to provide wireless coverage to terrestrial radio terminals. There are many advantages of using aerial platforms to provide wireless coverage, including larger coverage in remote areas and better line-of-sight conditions, etc. Energy is a scarce resource for the AeBSs, hence the wise management of energy is quite beneficial for the aerial network. In this context, we study the means of reducing the total energy consumption by designing and implementing an energy efficient AeBSs as presented in this paper. Implementing the sleep mode in the Base Stations (BSs) has been proven to be a very good approach for improving the energy efficiency and we propose a novel strategy for further improving energy efficiency by considering ternary state transceivers for AeBSs. Using the three state model, we propose a Markov Decision Process (MDP) based algorithm, which intelligently switches among three states of the transceivers based on the offered traffic meanwhile maintaining a prescribed minimum channel rate per user. We define a reward function for the MDP, which helps us to get an optimal policy for selecting a particular mode for the transceivers of the AeBS. Considering an AeBS with transceivers whose states are changeable, we perform simulations to analyse the performance of the algorithm. Our results show that, compared with the always active model, around 40% gain in the energy efficiency is achieved by using our proposed MDP algorithm together with the three-state transceivers model. We also show the energy-delay tradeoff in order to design an efficient AeBS. Keywords: Aerial base station, UAV, Green communication, Sleep mode, Markov decision process, Energy efficiency, Energy delay tradeof