Browsing by Author "Nyakikotyo, John Martin"

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    Performance evaluation of VSAT systems for ku & ka bands under rain conditions in Tanzania
    (University of Dar es Salaam, 2014) Nyakikotyo, John Martin
    The performance of Ku and Ka bands for VSAT systems has been carried out in Dar es Salaam, Kigoma and Mbeya. The three Regions, whose rain characteristics differ, were selected to represent the rainfall characteristic distribution of Tanzania. The coastal, Western and Southern highlands were represented by the respective Regions. The study chose them purposely to fit the required criteria set forth for the proper evaluation of all Tanzania country through projection of the obtained results. The ITU-R model was used to predict rainfall rate and rain attenuation in the selected Regions and it was validated by measured rain data taken from TMA, TANAPA and UDSM library for the three chosen Regions. The measured data were used to estimate the rain attenuation. Then modified model for the estimation and calculation of the rainfall rate and rain attenuation were presented respectively. The differences observed between the modified and measured parameters were of 2% order, hence validating the measured data. Results show that proposed rain rate model agrees with measured data by 99.8%. The rain rates estimated by using measured data disagree with ITU-R by more than 40 mm/hr for each selected region. The estimated attenuations also gave a difference of more than 3 dB with the ITU-R model. Carrier to noise power ratio (C/N) is computed, giving 11.1 dB for Ka and 41.6 dB for Ku in Mbeya region and for Kigoma region 32.5 dB for Ka and 50.5 dB for Ku band. In Dar es Salaam region, C/N is 16.4 dB for Ka and 44.5 dB for Ku band. It is concluded that for a feasible VSAT link using Ka and Ku bands, the C/N values should be at least 11.5 dB.