Self-Optimization of Coverage and Capacity in LTE using Adaptive Antenna Systems

In cellular radio networks, the selection of antenna parameters and techniques for antennas plays a key role for capacity and coverage area. Not only network performance is affected by suboptimal network planning but also it is affected by the dynamic radio environment. Therefore, antenna parameters should be adjusted adaptively. Since reacting to the changed situation manually is very expensive and time consuming, The Third Generation Partnership Project (3GPP) introduced the Coverage and Capacity Optimization (CCO) use case for Long Term Evolution (LTE) under the topic of Self-Organizing Network (SON). This thesis work provides a detailed analysis of the optimization space of antenna parameters and compares different tilt techniques as well as discusses vertical sectorization as a novel capacity optimization approach. The work continues by further focusing on the self optimization of coverage and capacity using Adaptive Antenna Systems (AAS) on the basis of findings in the previous simulations on antenna parameters. Evaluations are performed by mapping link-level simulation results into a system level LTE simulator that models antennas in details and propagation in three dimensions

Optimization in Self-Organizing Cellular Networks

Radio Access Technologies (RATs) continuously evolve as a response to the ever-growing demand for various services ranging from mobile broadband to machine-type communications. On the other hand, the evolution of RATs as in Long Term Evolution (LTE), is not sufficient alone to guarantee the coverage and capacity needs in cellular networks. This is because the overall Radio Access Network (RAN) performance does not only depend on the RAT capabilities but also the RAN parameters adjusted according to the network planning assumptions. Yet these assumptions may change in time, especially due to deployment densification, resulting in suboptimal RAN performance. Furthermore, base station outage or structural changes in the deployment area could impact the RAN performance. Since reacting on these inherent scenarios manually is very expensive and time consuming, automated recovery and optimization of cellular networks, i.e., Self-Organizing Networks (SON), was addressed as an essential technology component within the evolution of LTE standards. The work presented in this doctoral dissertation contributed to the development of the SON framework by analyzing the potential impact of adaptable RAN parameters on the system performance, designing practical SON algorithms and providing guidelines for SON architecture evolution toward the 5th Generation (5G). To assess the network performance, both analytical and experimental frameworks were developed based on the 3rd Generation Partnership Project (3GPP) guidelines. Whilst the analytical framework simplifies the link-level modeling, the system-level modeling enables the evaluation of overall network performance with a large number of RAN parameters. In the system-level simulations, the recommended 3GPP urban and suburban scenarios (with regular cell layouts) are assumed for the performance evaluations. In addition, the downtown Helsinki scenario is adopted for the SON performance analysis in a deployment model with an irregular cell layout. Performance evaluations reveal that antenna configuration impacts the coverage and capacity performance significantly. Furthermore, the results obtained for a realistic urban deployment verify that antenna optimization processes can be managed by both centralized and distributed SON architecture options. In addition, the studies demonstrate that cross-channel resource optimization could improve the network capacity in uplink by means of the localized SON architecture. Toward 5G, context-aware SON solutions were also considered. The long-term scheduling of delay-tolerant services in heterogeneous networks was selected as an example. The study assumes a novel SON architecture that is of User Equipment (UE) extension to involve UE context in decision-making. Approximate gains are revealed to address the potential of SON architecture evolution in 5G

Anencephalic fetuses can be an10 alternative for kidney transplantation, a stereological and histological investigation

In the study, stereological, histological, and anatomical techniques were used to investigate structural and morphometrical features of anencephalic and normal fetal kidneys. Twenty human fetal kidneys (5 male and 5 female anencephalic fetuses, and 5 male and 5 female normal fetuses) at gestational ages 30 to 35 weeks were examined. Our study used two basic research methods. One was conventional anatomical measurement at the macroscopic level, such as volume, length, weight, etc. The other consisted of conventional and modern microscopic techniques. The microscopic techniques were based on two research methods: histopathological examination at light microscopic level and stereological estimations, including mean kidney volumes, obtained by the Cavalieri method, and the total number and mean height of the glomeruli via the physical dissector method. There was no statistical difference between the two groups in terms of width, height, weight, and fluid replacement volumes. Microscopic quantitative assessment found no statistical differences either, in terms of the kidney volumes and the number and height of the glomeruli. Our findings suggest that kidneys from anencephalic infants may be a suitable alternative for renal transplantatio

Computerized Tomography-Guided Stereotactic Biopsy of Intracranial Lesions: Report of 500 Consecutive Cases

AIM: Computed tomography (CT)-guided stereotactic brain biopsy has been performed in our clinic since March 1998. In this prospective study, we examined the patient data undergoing stereotactic biopsy and the results of biopsies in 500 consecutive patients

Treatment delays and in-hospital outcomes in acute myocardial infarction during the COVID-19 pandemic: A nationwide study

© 2020 by Turkish Society of Cardiology.Objective: Delayed admission of myocardial infarction (MI) patients is an important prognostic factor. In the present nationwide registry (TURKMI-2), we evaluated the treatment delays and outcomes of patients with acute MI during the Covid-19 pandemic and compaired with a recent pre-pandemic registry (TURKMI-1). Methods: The pandemic and pre-pandemic studies were conducted prospectively as 15-day snapshot registries in the same 48 centers. The inclusion criteria for both registries were aged ≥18 years and a final diagnosis of acute MI (AMI) with positive troponin levels. The only difference between the 2 registries was that the pre-pandemic (TURKMI-1) registry (n=1872) included only patients presenting within the first 48 hours after symptom-onset. TURKMI-2 enrolled all consecutive patients (n=1113) presenting with AMI during the pandemic period. Results: A comparison of the patients with acute MI presenting within the 48-hour of symptom-onset in the pre-pandemic and pandemic registries revealed an overall 47.1% decrease in acute MI admissions during the pandemic. Median time from symptom-onset to hospital-arrival increased from 150 min to 185 min in patients with ST elevation MI (STEMI) and 295 min to 419 min in patients presenting with non-STEMI (NSTEMI) (p-values <0.001). Door-to-balloon time was similar in the two periods (37 vs. 40 min, p=0.448). In the pandemic period, percutaneous coronary intervention (PCI) decreased, especially in the NSTEMI group (60.3% vs. 47.4% in NSTEMI, p<0.001; 94.8% vs. 91.1% in STEMI, p=0.013) but the decrease was not significant in STEMI patients admitted within 12 hours of symptom-onset (94.9% vs. 92.1%; p=0.075). In-hospital major adverse cardiac events (MACE) were significantly increased during the pandemic period [4.8% vs. 8.9%; p<0.001; age- and sex-adjusted Odds ratio (95% CI) 1.96 (1.20-3.22) for NSTEMI, p=0.007; and 2.08 (1.38-3.13) for STEMI, p<0.001]. Conclusion: The present comparison of 2 nationwide registries showed a significant delay in treatment of patients presenting with acute MI during the COVID-19 pandemic. Although PCI was performed in a timely fashion, an increase in treatment delay might be responsible for the increased risk of MACE. Public education and establishing COVID-free hospitals are necessary to overcome patients' fear of using healthcare services and mitigate the potential complications of AMI during the pandemic

Global variation in postoperative mortality and complications after cancer surgery: a multicentre, prospective cohort study in 82 countries

© 2021 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY-NC-ND 4.0 licenseBackground: 80% of individuals with cancer will require a surgical procedure, yet little comparative data exist on early outcomes in low-income and middle-income countries (LMICs). We compared postoperative outcomes in breast, colorectal, and gastric cancer surgery in hospitals worldwide, focusing on the effect of disease stage and complications on postoperative mortality. Methods: This was a multicentre, international prospective cohort study of consecutive adult patients undergoing surgery for primary breast, colorectal, or gastric cancer requiring a skin incision done under general or neuraxial anaesthesia. The primary outcome was death or major complication within 30 days of surgery. Multilevel logistic regression determined relationships within three-level nested models of patients within hospitals and countries. Hospital-level infrastructure effects were explored with three-way mediation analyses. This study was registered with ClinicalTrials.gov, NCT03471494. Findings: Between April 1, 2018, and Jan 31, 2019, we enrolled 15 958 patients from 428 hospitals in 82 countries (high income 9106 patients, 31 countries; upper-middle income 2721 patients, 23 countries; or lower-middle income 4131 patients, 28 countries). Patients in LMICs presented with more advanced disease compared with patients in high-income countries. 30-day mortality was higher for gastric cancer in low-income or lower-middle-income countries (adjusted odds ratio 3·72, 95% CI 1·70–8·16) and for colorectal cancer in low-income or lower-middle-income countries (4·59, 2·39–8·80) and upper-middle-income countries (2·06, 1·11–3·83). No difference in 30-day mortality was seen in breast cancer. The proportion of patients who died after a major complication was greatest in low-income or lower-middle-income countries (6·15, 3·26–11·59) and upper-middle-income countries (3·89, 2·08–7·29). Postoperative death after complications was partly explained by patient factors (60%) and partly by hospital or country (40%). The absence of consistently available postoperative care facilities was associated with seven to 10 more deaths per 100 major complications in LMICs. Cancer stage alone explained little of the early variation in mortality or postoperative complications. Interpretation: Higher levels of mortality after cancer surgery in LMICs was not fully explained by later presentation of disease. The capacity to rescue patients from surgical complications is a tangible opportunity for meaningful intervention. Early death after cancer surgery might be reduced by policies focusing on strengthening perioperative care systems to detect and intervene in common complications. Funding: National Institute for Health Research Global Health Research Unit

Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

© 2022 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 licenseBackground: Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide. Methods: A multimethods analysis was performed as part of the GlobalSurg 3 study—a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital. Findings: Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3·85 [95% CI 2·58–5·75]; p<0·0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63·0% vs 82·7%; OR 0·35 [0·23–0·53]; p<0·0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer. Interpretation: Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised. Funding: National Institute for Health and Care Research