Abstract
Path loss is the primary factor that determines the overall coverage of networks. Designing reliable wireless communication systems requires accurate path loss prediction models. Future wireless mobile systems will rely mainly on the super-high frequency (SHF) and the millimeter-wave (mmWave) frequency bands due to the massive available bandwidths that will meet projected users’ demand, such as the needs of the fifth-generation ( $5G$ ) wireless systems and other high-speed multimedia services. However, these bands are more sensitive and exhibit a different propagation behavior compared to the frequency bands below $6~GHz$ . Hence, improving the existing models and developing new models are vital for characterizing the wireless communication channel in both indoor and outdoor environments for future SHF and mmWave services. This paper proposes an efficient improvement of the well-known close-in (CI) free space reference distance model and the floating-intercept (FI) model. Real measured data was taken for both line-of-sight (LOS) and non-line-of-sight (NLOS) communication scenarios in a typical indoor corridor environment at three selected frequencies within the SHF band, namely $14~GHz$ , $18~GHz$ , and $22~GHz$ . The research finding of this work reveals that the proposed models have better performance in terms of their accuracy of fitting real measured data collected from measurement campaigns. In addition, this work studies the impact of the angle of arrival and the antenna heights on the current and improved CI and FI models. The results show that the improved models provide better stability and sensitivity to the change of these parameters. Furthermore, the mean square error between the models and their improved versions were presented. Finally, this paper shows that shadow fading’s standard deviation can have a notable reduction in both the LOS and NLOS scenarios (especially in the NLOS), which means higher precision in predicting the path loss.
Highlights
Era after era, the demand for higher mobile data traffic is exponentially increasing due to the tremendous revolution in technologies relying totally on mobile networks and their services
It is presented in two subsections, each one compares a model with its improved version at the three frequencies (14, 18, and 22 GHz) for both the LOS and NLOS scenarios
It is clear from the figure that both models fit the measured path loss adequately and both have a comparable performance with a slight preference of the improved model
Summary
The demand for higher mobile data traffic is exponentially increasing due to the tremendous revolution in technologies relying totally on mobile networks and their services. The CI model can be written from Eq (3) by replacing k1 by the value of the free space path loss at the operating frequency (f ) and the reference distance (d0), and replacing k2 by the PLE (n) as described in the following equation: PLCI (d)[dB] = FSPL(f , d0) + 10n log10(d) + XσCI , (5). We adopted the physically-based reference distance to be 1 m for the reason that the wireless signals at the frequency bands above 6 GHz exhibit significant path loss values in the first meter of the propagation away from the transmitting antenna [29]. The improved model has two terms that depend on the 3D Tx-Rx separation distance This means that the path loss exponent principle exists in two parameters (n1 and n2), as presented in the following equation: PLImp. CI (d)[dB] = FSPL(f , d0) + 10n1 log10(d) + 10n2(log10(d))2 +XσImp.CI , d > 1m, (7). The models have comparable overall performance in predicting the path loss with a preference of one over the other depending on the operating frequency as well as the environment and communication scenario of the wireless communication system [10], [57], [58]
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