Empirical Outdoor-to-Indoor Propagation Path Loss Models Investigation and Tuning for 900, 1800 & 2100 MHz Frequencies: the Case of Addis Ababa City

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As trend of cellular traffic shifts from voice dominant to data and most of this traffic is being generated from indoor environment, providing optimal indoor solutions is becoming prime target of a radio planning task. But, it is a challenging task to meet the radio signal coverage target that ensures signal quality required by data traffic in indoor environment as radio propagation is impacted by building penetration loss (BPL) and in building propagation path loss. Hence, to ensure radio signal coverage target in such environment it is required to closely investigate and characterize these two losses. Investigating and characterizing these losses is prominently important for vertically expanding cities like Addis Ababa, Ethiopia, where outdoor macro sites are predominant solution to avail indoor environment signal coverage targets. This thesis aims to accomplish this critical task for city of Addis Ababa. Representative sample buildings based on morphology, purpose, building material types and building to transmitter antenna height relation are selected. Moreover, commonly used indoor propagation models are identified. Measurement is undertaken, based on measurement it is attempted to estimate BPL and tuned model parameters for the selected propagation models for various categories of indoor environments to determine unified outdoor-to-indoor propagation model. The results indicate that for a frequency of 900MHz, BPL for buildings made from hollow concrete blocks/bricks is identified as 12.01dB to 17.7dB; for building made from stone masonry the value ranges from 15.11dB to 17.81dB; and from 2.46dB to 8.81dB for buildings mainly made from glass. For 1800MHz frequency the identified BPL results are: 13.7dB to 17.51dB for buildings made from hollow concrete blocks/bricks; 16.38dB to 25.41dB for buildings made from stone masonry; and 0.89dB to 8.14dB for buildings mainly made from glass. Similarly, BPL for 2100MHz frequency is identified as 12.22dB to 13.36dB for buildings made from hollow concrete blocks/bricks; 14.16dB to 19..66dB for buildings made from stone masonry; and 6.25dB to 10.36dB for buildings mainly made from glass. Then, for the measured indoor path loss, parameters of the Path Loss Slope (PLS) model were tuned to capture radio signal propagation characteristics in the indoor environments. The results indicate that, the path loss exponent is found out to be in the range of 0.52 to 2.09 depending on the indoor environment considered. To validate the models, Root Mean Square Error (RMSE) is computed and it is found out it ranges from 1.06dB to 5.25dB depending on different building environments and selected models. The resulting outdoor-to-indoor propagation models can be used for coverage planning in the city of Addis Ababa.



Building penetration loss, Path loss Outdoor-to-indoor models, Tuning