Performance analysis of a WiMAX system under jamming

Maailmanlaajuinen elintason nousu ja teknologinen kehitys ovat synnyttäneet idean laajakaistayhteyden tarjoamisesta myös harvaanasutuille alueille. Tämä tarve on nostettu esille myös Suomessa valtioneuvoston laajakaistastrategiassa. IEEE 802.16 standardin mukainen WiMAX on tulevaisuuden langaton teknologia, joka mahdollistaa perustason laajakaistakäyttöön riittävät yhteysnopeudet taloudellisessa mielessä kohtuullisin investoinnein. WiMAX on kehittyvä teknologia, jonka soveltuvuuden tutkiminen erilaisiin käyttötarkoituksiin on keskeistä. Tässä diplomityössä tutkitaan skenaarioiden avulla yhden IEEE 802.16-2004 mukaisen järjestelmän toimivuutta häirinnän alaisena suhteessa standardin asettamiin vaatimuksiin. Häirintätyypit on valittu perusteena niiden helppo toteutettavuus, jolloin ne vastaavat myös luonnollisessa ympäristössä usein esiintyviä häiriösignaaleja. Järjestelmän suorituskyvyn havaittiin poikkeavan selvästi eri häiriötyypeillä ja näin voitiin erottaa selkeästi ominaisuuksia, joihin järjestelmäkehityksessä tulisi tulevaisuudessa panostaa. Lisäksi järjestelmän toiminnasta löydettiin joitakin perusteorian kannalta tarkasteltuna yllättäviä ominaisuuksia, esimerkiksi pilottialikantoaaltojen häirintäherkkyyksissä havaittiin lähes 10 desibelin eroja. Kokonaisuudessaan työ pyrkii antamaan selkeän kuvan järjestelmän tämän hetkisestä suorituskyvystä niin häirinnänalaisena, mutta myös toiminta häiriöttömässä ympäristössä selviää mittaustulosten analyysistä. Jotkin häirintätavat heikentävät järjestelmän toimintakykyä nopeasti, joten käyttöönottopäätöksen tekemiseksi tarvitaan etukäteistietoa mahdollisesti esiintyvistä häirintämuodoista.Worldwide techno-economical development has brought up an idea of offering wideband connections also to suburban and even rural areas. In Finland this has been conceptualised as national wideband strategy (Laajakaistastrategia). IEEE 802.16 WiMAX is a future technology which could provide users in rural areas with adequate connection speeds for basic wideband use with reasonable financial investments. Being a developing technology, the research that focuses on studying the suitability of WiMAX in different operating environments is of great importance. In this thesis, a IEEE 802.16-2004 based system under jamming is evaluated in terms of the requirements set by the standard. The selection of the used jamming forms is justified by the easiness of generation, so that they could also exist in a natural environment. The performance of the system was found out to greatly differ with the use of different jamming signals, allowing central areas to be identified, where system development should be focused on. In addition, from the basic theory point of view, rather surprising results where also found as some of the pilot subcarriers needed almost 10 dB less jamming power than others to cause the same portion of errors. The work should give a clear picture of how the studied WiMAX system performs as well under jamming as without the presence of jamming. The results show that some forms of interference degrade the performance of the system rapidly, thus the form of incoming jamming should be known and considered before deploying the system

Analysis of competition in the mobile phone markets of the United States and Europe

Competition in an economic context is a widely studied phenomenon with a significant body of accumulated research and theory. However, competition in the mobile phone industry, despite its prevalence in public discussion, has received significantly less attention in academic research. Within the international business (IB) context there are very few academic studies that seek to analyze and compare the different geographical mobile phone markets from the viewpoint of competition. This thesis examines competition in the mobile phone markets of the United States and Europe in light of interviews and secondary data covering years 2002 - 2011. The framework used for the analysis is founded on concepts drawn primarily from industrial organization (IO) economics, IB theory and micro-economics. The first part of the thesis gives an overview of the U.S. and European mobile phone markets and the second part focuses specifically on Nokia, its actions and performance on the U.S. market. The findings reveal that the U.S. and European mobile phone markets are fundamentally different. Firstly, while in Europe several parallel sales channels exist, the U.S. market is dominated by mobile operators that control access to the end customer. Secondly, in the U.S. market phones are generally sold heavily subsidized and bundled, and either under the operator brand or co-branding agreements. In addition, the U.S. market has historically split in two technologies, GSM and CDMA, as opposed to Europe where GSM is the dominant technology. The analysis of Nokia in the United States shows that the company’s problems appear to be related to the very characteristics of the U.S. market and the way Nokia has reacted. First and foremost, Nokia has had a difficult relationship with the operators who have required tailoring, technology variations etc. In addition to its focus on GSM, Nokia seems to have refused to tailor for operators and insisted on sales under the Nokia brand. Finally, over the years, Nokia’s situation has been complicated by occasional disputes related e.g. to immaterial property rights and recently problems in developing and having operators represent especially Nokia’s high-end models

Transcatheter and surgical aortic valve replacement in patients with bicuspid aortic valve

Objectives To compare the outcomes after surgical (SAVR) and transcatheter aortic valve replacement (TAVR) for severe stenosis of bicuspid aortic valve (BAV). Methods We evaluated the early and mid-term outcome of patients with stenotic BAV who underwent SAVR or TAVR for aortic stenosis from the nationwide FinnValve registry. Results The FinnValve registry included 6463 AS patients and 1023 (15.8%) of them had BAV. SAVR was performed in 920 patients and TAVR in 103 patients with BAV. In the overall series, device success after TAVR was comparable to SAVR (94.2% vs. 97.1%, p = 0.115). TAVR was associated with increased rate of mild-to-severe paravalvular regurgitation (PVR) (19.4% vs. 7.9%, p <0.0001) and of moderate-to-severe PVR (2.9% vs. 0.7%, p = 0.053). When newer-generation TAVR devices were evaluated, mild-to-severe PVR (11.9% vs. 7.9%, p = 0.223) and moderate-to-severe PVR (0% vs. 0.7%, p = 1.000) were comparable to SAVR. Type 1 N-L and type 2 L-R/R-N were the BAV morphologies with higher incidence of mild-to-severe PVR (37.5% and 100%, adjusted for new-generation prostheses p = 0.025) compared to other types of BAVs. Among 75 propensity score-matched cohorts, 30-day mortality was 1.3% after TAVR and 5.3% after SAVR (p = 0.375), and 2-year mortality was 9.7% after TAVR and 18.7% after SAVR (p = 0.268) Conclusions In patients with stenotic BAV, TAVR seems to achieve early and mid-term results comparable to SAVR. Type 1 N-L and type 2 L-R/R-N BAV morphologies had higher incidence of PVR. Larger studies evaluating different phenotypes of BAV are needed to confirm these findings. [GRAPHICS] .Peer reviewe

Subtype of atrial fibrillation and the outcome of transcatheter aortic valve replacement: The FinnValve Study

Whether the subtype of atrial fibrillation affects outcomes after transcatheter aortic valve replacement for aortic stenosis is unclear. The nationwide FinnValve registry included 2130 patients who underwent primary after transcatheter aortic valve replacement for aortic stenosis during 2008–2017. Altogether, 281 (13.2%) patients had pre-existing paroxysmal atrial fibrillation, 651 (30.6%) had pre-existing non-paroxysmal atrial fibrillation and 160 (7.5%) were diagnosed with new-onset atrial fibrillation during the index hospitalization. The median follow-up was 2.4 (interquartile range: 1.6–3.8) years. Paroxysmal atrial fibrillation did not affect 30-day or overall mortality (p-values >0.05). Non-paroxysmal atrial fibrillation demonstrated an increased risk of overall mortality (hazard ratio: 1.61, 95% confidence interval: 1.35–1.92; p0.05). In conclusion, non-paroxysmal atrial fibrillation and new-onset atrial fibrillation are associated with increased mortality after transcatheter aortic valve replacement for aortic stenosis, whereas paroxysmal atrial fibrillation has no effect on mortality. These findings suggest that non-paroxysmal atrial fibrillation rather than paroxysmal atrial fibrillation may be associated with structural cardiac damage which is of prognostic significance in patients with aortic stenosis undergoing transcatheter aortic valve replacement.Peer reviewe

Perioperative Bleeding Requiring Blood Transfusions is Associated With Increased Risk of Stroke After Transcatheter and Surgical Aortic Valve Replacement

Objectives: The authors aimed to investigate the impact of severe bleeding and use of red blood cell (RBC) transfusion on the development of postoperative stroke after surgical (SAVR) and transcatheter aortic valve replacement (TAVR), taken from the FinnValve registry. Design: Nationwide, retrospective observational study. Setting: Five Finnish university hospitals participated in the registry. Participants: A total of 6,463 patients who underwent SAVR (n = 4,333) or TAVR (n = 2,130). Interventions: Patients who underwent TAVR or SAVR with a bioprosthesis with or without coronary revascularization. Measurements and Main Results: The incidence of postoperative stroke after SAVR was 3.8%. In multivariate analysis, the number of trans-fused RBC units (odds ratio [OR], 1.098; 95% confidence interval [CI], 1.064-1.133) was one of the independent predictors of postoperative stroke. The incidence of stroke increased, along with the severity of perioperative bleeding, according to the European Coronary Artery Bypass Grafting (E-CABG) bleeding grades were as follows: grade 0, 2.2% (reference group); grade 1, 3.4% (adjusted OR, 1.841; 95% CI, 1.105-3.066); grade 2, 5.5% (adjusted OR, 3.282; 95% CI, 1.948-5.529); and grade 3, 14.8% (adjusted OR, 7.103; 95% CI, 3.612-13.966). The inci-dence of postoperative stroke after TAVR was 2.5%. The number of transfused RBC units was an independent predictor of stroke after TAVR (adjusted OR, 1.155; 95% CI, 1.058-1.261). The incidence of postoperative stroke increased, along with the severity of perioperative bleeding, as stratified by the E-CABG bleeding grades: E-CABG grade 0, 1.7%; grade 1, 5.3% (adjusted OR, 1.270; 95% CI, 0.532-3.035); grade 2, 10.0% (adjusted OR, 2.898; 95% CI, 1.101-7.627); and grade 3, 30.0% (adjusted OR, 10.706; 95% CI, 2.389-47.987). Conclusions: Perioperative bleeding requiring RBC transfusion and/or reoperation for intrathoracic bleeding is associated with an increased risk of postoperative stroke after SAVR and TAVR. Patient blood management and meticulous preprocedural planning and operative technique aiming to avoid significant perioperative bleeding may reduce the risk of cerebrovascular complications. (C) 2022 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)Peer reviewe

Ten-year experience with transcatheter and surgical aortic valve replacement in Finland

Aim: We investigated the outcomes of transcatheter (TAVR) and surgical aortic valve replacement (SAVR) in Finland during the last decade. Methods: The nationwide FinnValve registry included data from 6463 patients who underwent TAVR or SAVR with a bioprosthesis for aortic stenosis from 2008 to 2017. Results: The annual number of treated patients increased three-fold during the study period. Thirty-day mortality declined from 4.8% to 1.2% for TAVR (p = .011) and from 4.1% to 1.8% for SAVR (p = .048). Two-year survival improved from 71.4% to 83.9% for TAVR (p <.001) and from 87.2% to 91.6% for SAVR (p = .006). During the study period, a significant reduction in moderate-to-severe paravalvular regurgitation was observed among TAVR patients and a reduction of the rate of acute kidney injury was observed among both SAVR and TAVR patients. Similarly, the rate of red blood cell transfusion and severe bleeding decreased significantly among SAVR and TAVR patients. Hospital stay declined from 10.4 +/- 8.4 to 3.7 +/- 3.4 days after TAVR (p <.001) and from 9.0 +/- 5.9 to 7.8 +/- 5.1 days after SAVR (p <.001). Conclusions: In Finland, the introduction of TAVR has led to an increase in the invasive treatment of severe aortic stenosis, which was accompanied by improved early outcomes after both SAVR and TAVR.Peer reviewe

Transcatheter and Surgical Aortic Valve Replacement in Patients with Recent Acute Heart Failure

Background. Patients with severe aortic stenosis and heart failure have poor prognosis, and their outcomes may be suboptimal even after transcatheter (TAVR) and surgical aortic valve replacement (SAVR). Methods. This is an analysis of the nationwide FinnValve registry, which included patients who underwent primary TAVR or SAVR with a bioprothesis for aortic stenosis. We evaluated the outcome of patients with acute heart failure (AHF) within 60 days prior to TAVR or SAVR. Results. The prevalence of recent AHF was 11.4% (484 of 4241 patients) in the SAVR cohort and 11.3% (210 of 1855 patients) in the TAVR cohort. In the SAVR cohort, AHF was associated with lower 30-day survival (91.3% vs 97.0%; adjusted odds ratio 1.801, 95% confidence interval [CI] 1.125-2.882) and 5-year survival (64.0% vs 81.2%; adjusted hazard ratio 1.482, 95% CI 1.207-1.821). SAVR patients with AHF had higher risk of major bleeding, need of mechanical circulatory support, acute kidney injury, prolonged hospital stay, and composite end-point (30-day mortality, stroke and/or acute kidney injury). Patients with AHF had a trend toward lower 30-day survival (crude rates 95.2% vs 97.9%; adjusted odds ratio 2.028, 95% CI 0.908-4.529) as well as significantly lower 5-year survival (crude rates 45.3% vs 58.5%; adjusted hazard ratio 1.530, 95% CI 1.185-1.976) also after TAVR. AHF increased the risk of acute kidney injury, prolonged hospital stay, and composite end-point after TAVR. Conclusions. Recent AHF is associated with increased risk of mortality and morbidity after SAVR and TAVR. These findings suggest that aortic stenosis patients should be referred for invasive treatment before the development of clinically evident heart failure.Peer reviewe

Transcatheter and surgical aortic valve replacement in patients with left ventricular dysfunction

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Mid-term outcomes of Sapien 3 versus Perimount Magna Ease for treatment of severe aortic stenosis

BackgroundThere is limited information on the longer-term outcome after transcatheter aortic valve replacement (TAVR) with new-generation prostheses compared to surgical aortic valve replacement (SAVR). The aim of this study was to compare the mid-term outcomes after TAVR with Sapien 3 and SAVR with Perimount Magna Ease bioprostheses for severe aortic stenosis.MethodsIn a retrospective study, we included patients who underwent transfemoral TAVR with Sapien 3 or SAVR with Perimount Magna Ease bioprosthesis between January 2008 and October 2017 from the nationwide FinnValve registry. Propensity score matching was performed to adjust for differences in the baseline characteristics. The Kaplan-Meir method was used to estimate late mortality.ResultsA total of 2000 patients were included (689 in the TAVR cohort and 1311 in the SAVR cohort). Propensity score matching resulted in 308 pairs (STS score, TAVR 3.52.2% vs. SAVR 3.52.8%, p=0.918). In-hospital mortality was 3.6% after SAVR and 1.3% after TAVR (p=0.092). Stroke, acute kidney injury, bleeding and atrial fibrillation were significantly more frequent after SAVR, but higher rate of vascular complications was observed after TAVR. The cumulative incidence of permanent pacemaker implantation at 4years was 13.9% in the TAVR group and 6.9% in the SAVR group (p=0.0004). At 4-years, all-cause mortality was 20.6% for SAVR and 25.9% for TAVR (p=0.910). Four-year rates of coronary revascularization, prosthetic valve endocarditis and repeat aortic valve intervention were similar between matched cohorts.Conclusions p id=Par The Sapien 3 bioprosthesis achieves comparable midterm outcomes to a surgical bioprosthesis with proven durability such as the Perimount Magna Ease. However, the Sapien 3 bioprosthesis was associated with better early outcome.Trial registration p id=Par ClinicalTrials.gov Identifier: NCT03385915.Peer reviewe

Blood Transfusion and Outcome After Transfemoral Transcatheter Aortic Valve Replacement

Objective: To investigate the prognostic impact of red blood cell (RBC) transfusion on the outcome after transfemoral transcatheter aortic valve replacement (TAVR). Design: Nationwide, retrospective multicenter study. Setting: Five University Hospitals. Participants: The nationwide FinnValve registry included data from 2,130 patients who underwent TAVR for aortic stenosis from 2008 to 2017. After excluding patients who underwent TAVR through nontransfemoral accesses, 1,818 patients were selected for this analysis. Intervention: TAVR with or without coronary revascularization. Measurements and Main Results: RBCs were transfused in 293 patients (16.1%). Time-trend analysis showed that the rates of RBC transfusion decreased significantly from 27.5% in 2012 to 10.0% in 2017 (p <0.0001). Among 281 propensity score matched pairs, RBC transfusion was associated with higher 30-day mortality (7.1% v 0%, p <0.0001), late mortality (at 5-year, 59.1% v 43.3%, p = 0.008), as well as increased risk of acute kidney injury (17.0% v 4.4%, p <0.0001), renal replacement therapy (3.6% v 0.4, p <0.0001) and prolonged hospital stay (mean, 8.5 v 4.7 days, p <0.0001) compared with patients who did not receive blood transfusion. In the overall series, the risk of adverse events increased significantly with the increasing amount of transfused RBC units and when operation for excessive bleeding was necessary. Consistently with these findings, postoperative hemoglobin drop and nadir level were associated with higher early and late mortality. Conclusions: Patients who received blood transfusion after TAVR had an increased risk of early and late adverse events. These adverse effects were particularly evident with increasing amount of RBC transfusion and operations for excessive bleeding. (C) 2019 Elsevier Inc. All rights reserved.Peer reviewe