New Coding/Decoding Techniques for Wireless Communication Systems

Wireless communication encompasses cellular telephony systems (mobile communication), wireless sensor networks, satellite communication systems and many other applications. Studies relevant to wireless communication deal with maintaining reliable and efficient exchange of information between the transmitter and receiver over a wireless channel. The most practical approach to facilitate reliable communication is using channel coding. In this dissertation we propose novel coding and decoding approaches for practical wireless systems. These approaches include variable-rate convolutional encoder, modified turbo decoder for local content in Single-Frequency Networks, and blind encoder parameter estimation for turbo codes. On the other hand, energy efficiency is major performance issue in wireless sensor networks. In this dissertation, we propose a novel hexagonal-tessellation based clustering and cluster-head selection scheme to maximize the lifetime of a wireless sensor network. For each proposed approach, the system performance evaluation is also provided. In this dissertation the reliability performance is expressed in terms of bit-error-rate (BER), and the energy efficiency is expressed in terms of network lifetime

Clinical and Socio-demographic Profile of the First 33 COVID-19 Cases Treated at Dedicated Treatment Center in Ethiopia

BACKGROUND:Severe respiratory tract infection caused by family of Corona viruses has become world pandemic. The purpose of this study was to describe the first few COVID 19 cases in Ethiopia.METHOD: Descriptive study was conducted on the first 33 consecutive RT-PCR confirmed COVID 19 cases diagnosed and managed at Ekka-Kotebe COVID Treatment Center in Addis Ababa, Ethiopia.RESULT: The median age of the cases was 36 years. Cough, headache and fever were the most frequent symptoms. Diarrhea, sore throats, loss of taste and/or smell sensation were among the rare symptoms. Most (84.8%) had mild to moderate disease, and 15.2%(n=5) were critical at the time of admission. Among the five ICU admissions, four patients required invasive mechanical ventilation. Thirty cases were discharged after two pairs of nasopharyngeal and oropharyngeal samples turned negative for SARS CoV2. Three cases from the ICU died while on mechanical ventilator. The age of the two deaths was 65 years, and one was 60 years. With the exception of three, all cases were either imported from abroad or had contact with confirmed cases.CONCLUSION: Most of our patients were in the younger age group with male predominance and few with comorbidities. Cough was the commonest symptom followed by headache and fever. As it was in the early stage of the pandemic, observation of more cases in the future will reveal further clinical and demographic profiles of COVID-19 cases in Ethiopia

Clinical Characteristics and Treatment Outcomes of COVID-19 Patients at Eka Kotebe General Hospital, Addis Ababa, Ethiopia

Data from much of Africa are still scarce on the clinical characteristics, outcomes of treatment, and factors associated with disease severity and mortality of COVID-19. A cross-sectional study was conducted at Eka Kotebe General Hospital, Ethiopia\u27s first COVID-19 treatment center. All consecutive symptomatic SARS CoV-2 RT-PCR positive individuals, aged 18 and older, admitted to the hospital between March 13 and September 16, 2020, were included. Of the total 463 cases, 319 (68.9%) were male. The median age was 45 years (interquartile range 32-62). The most common three symptoms were cough (69%), shortness of breath (SOB; 44%), and fatigue (37%). Hypertension was the most prevalent comorbidity, followed by diabetes mellitus. The age groups 40 to 59 and ≥ 60 were more likely to have severe disease compared with those \u3c 40 years of age (adjusted odds ratio [aOR] = 3.45, 95% confidence interval [CI]: 1.88-6.31 and aOR = 3.46, 95% CI: 1.91-6.90, respectively). Other factors associated with disease severity included the presence of any malignancy (aOR = 4.64, 95% CI: 1.32-16.33) and SOB (aOR = 3.83, 95% CI: 2.35-6.25). The age group ≥ 60 was significantly associated with greater in-hospital mortality compared with those \u3c 40 years. In addition, the presence of any malignancy, SOB, and vomiting were associated with higher odds of mortality. In Ethiopia, most COVID-19 patients were male and presented with cough, SOB, and fatigue. Older age, any malignancy, and SOB were associated with disease severity; these factors, in addition to vomiting, also predicted mortality