Absfrad-We study via computer simulation the computation of the outside-cell interference factor f for cellular codedivision multiple access (CDMA) wireless communication systems. This factor is inversely pmportional to system capacity, and so its computation is of great practical interest. To date, all studies have focused on the mean value off, without regard to its extrema or temporal dynamics. We compute values of the extrema for several propagation path loss exponents and wer velocities, and show that the maximum value off can be many times its mean value, and f can change as rapidly as the mobile user Doppler spread.

Purpose: The purpose of this study was to assess the performance of the tertiary centers (TCS) and vision centers (VCs) of the four organizations participating in this research, once the lockdown was lifted, and to compare it with the performance during the same period of the previous year. Methods: This was a cross-sectional study assessing eyecare utilization in the first 2 months after resumption of services post the lockdown in 2020 and comparing that across the same time period in 2019. Anonymized data containing basic demographic details, proportions of patient visits and their reasons, as well as referral information was collected. The drop percentage method was used, and P values were calculated using paired t -tests. Results: Four TCs and 60 VCs were included. Overall, outpatient attendance dipped 51.2% at TCs and 27.5% at VCs, across the 2 years. At both levels of care delivery, the percentage drop in females was more than that in males; however, the overall drop at VCs was less than that at TCs, for both sexes. Eyecare utilization in pediatric populations dropped significantly more than in adult populations, across the overall sample. There was no significant change in referrals for refractive error as a proportion of total outpatients, although there was a significant decline in the same for cataract and specialty treatment. Conclusion: VCs are valuable and successful model for eyecare delivery especially in the continued aftermath of the COVID-19 pandemic.

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Cognitive radio network is an emerging solution to deal with spectrum scarcity and to utilize the radio spectrum in opportunistic and efficient manner.Secure data transmission is one of the important issues in these kind of networks. This work studies the secrecy outage performance of a multiple-input multiple-output underlay cognitive wiretap radio network system over Rayleigh fading channel with delayed channel state information. This work considers that the secondary transmitter is equipped with multiple antennas and confidential information is transmitted from to multiantenna receiver in the presence of multiantenna eavesdropper. Further, the transmit antenna selection scheme is considered at secondary transmitter to reduce the complexity of antenna selection and to make it more practicable. To improve the quality of signal, this work considers maximal ratio combining (MRC) at secondary receiver, while selection combining and MRC techniques are utilized at the eavesdropper. The closed form expression for exact, asymptotic, and intercept secrecy outage probability has been derived, and the simulation is done for the validation of analytical results. The derived results reveal deterioration of channel secrecy performance with outdated channel state information, and the eavesdropper with outdated channel state information has also an adverse effect. Moreover, the diversity order that can be achieved in underlay cognitive radio network with outdated channel state information is unity.

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