Empirical stairwell propagation models for long term evolution applications

Abstract

This thesis presents investigation of path loss, PL, and shadowing, Xσ, of signal wave along and about multi floor stairways that have dog-leg stairwell configuration. The objective is to develop frequency-dependent empirical propagation models that could approximate PL and Xσ for two conditions. The first condition is when both transmitter, Tx, and receiver, Rx, are within the stairwell structure. The second condition is when either one of the Tx or Rx is inside adjacent rooms to the stairwells. Attention was also drawn towards the influence of stair flights and floor height to attenuation of signal wave as it propagates within the stairwell. Analysing the impact of the aforementioned structures within the stairwell, signal wave propagating between stairwell and adjacent in-building space as well as developing frequency-dependant empirical propagation model are research areas which have yet to be covered by previous propagation studies pertaining to multi floor stairway. Frequencies of interest, f, ranged from 0.7 GHz up to 2.5 GHz that cover various long term evolution (LTE) and public safety communication bands. Research works involved measurement campaign in four different multi-floor buildings inside Universiti Teknologi Malaysia’s campus. PL’s relations with separation distance between Tx and Rx, d, and f were formulated with auxiliary site-specific terms added to improve two proposed empirical propagation models. It was found that for signal wave propagation where both Tx and Rx were within the stairwell, placing Rx at elevated or lower position than Tx does not influence significantly recorded PL data. However, for propagation between stairwell and adjacent rooms, placing Rx at elevated or lower than Tx may influence significantly recorded PL data. Suitable measurement campaign planning was arranged in the light of this finding. The proposed models were then examined and compared with ITU-R, COST and WINNER II indoor empirical propagation models. From measurement in dedicated testing sites, it was demonstrated that the proposed models have the smallest computed mean, μR, relative to the other standard models. The largest μR was -2.96 dB with a 3.34 dB standard deviation, σR. On the other hand, results from COST, ITU-R and WINNER II models demonstrated lower precision in all inspected settings, with the largest μR being 8.06 dB, 7.71 dB and 15.98 dB respectively and their σR being 3.79 dB, 6.82 dB and 9.40 dB accordingly. The results suggest that the proposed PL models, which considered the impact of building structures within and about the stairwell could provide higher PL prediction’s accuracy for wireless communication planning pertaining to the stairwell environment, particularly for public safety responders.