Wireless ad hoc network is a self-configurable and dynamically distributed network in which stations can move freely. In the ad hoc network, some flows have difficulty in accessing the channel due to contention at both the medium-access control (MAC) and link layers. The IEEE 802.11 protocol is currently the de facto standard for wireless networks. It uses enhanced distributed channel access (EDCA) method to access the transmission environment of each type of data flow. The size of the contention window (CW) in EDCA is related to the probability of accessing the channel of each flow. In our approach, useful information is obtained from the physical, MAC, and link layers. A fuzzy logic system is then used to adjust the size of CW to rely on such value, thereby improving the fairness index of data flows (voice, video, best effort) in IEEE 802.11 EDCA. The simulation results show that the proposed method can improve the throughput and fairness index of data flows.

ABSTRACT Objective: describe the clinical features in chronic sinusitis in adults in National Otorhinorarynology Hospital of Vietnam. Subjects and research methods: use the transverse descriptive method to describe the clinical features in chronic sinusitis in adults in the inpatient department - National otolaryngology hospital of Viet Nam. Results: the study involved 58 patients aged 18 and over suffering from chronic sinusitis in the inpatient department - National Otorhinorarynology Hospital of Vietnam from August 2019 to December 2019. The average age of the patients is 47,17 ± 15,32, with a male to female ratio of 1.1:1; most of the reason for being hospitalized is runny nose (72,4%) and stuffy nose (87,9%). Symptoms encountered in chronic sinusitis are runny nose, stuffy nose, headache, smell disorders and cough, in addition, with systemic symptoms such as fever, fatigue, weakness. Conclusion: on the clinical characteristics of chronic sinusitis in adults, the common symptoms in chronic sinusitis are runny nose, stuffy nose, headache, smell disorders and cough, duration of illness lasts from                 6 months to many years, in both men and women.

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