This work focuses on the characterization of indoor hybrid power line communication (PLC)-wireless channels in the frequency band between 1.7 and 100 MHz. These hybrid channels allow the simultaneous exploitation of the ubiquitous PLC channel and the mobility benefits offered by the wireless signals radiating from and being induced into power cables. A comprehensive study and analysis was conducted based on: (i) coherence time, (ii) additive noise power spectral density, (iii) coherence bandwidth, (iv) delay spread, (v) average channel gain, (vi) channel frequency response and (vii) channel capacity. Based on the reported analysis, the magnitude responses of hybrid PLC-wireless channels can be assumed to be symmetrical and significantly frequency selective. Also, we reveal that additive noise power spectral density and, consequently, channel capacity differ considerably in the PLC-to-wireless and wireless-to-PLC transmission directions. Finally, we show that the measured PLCwireless channels present a channel capacity of up to hundreds mega bits per second.

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This paper presents a statistical modeling of rain attenuation in terrestrial links located in a tropical region using different types of distribution. Each distribution is tested against long-term statistics of data collected during up to two years of experimental measurements in links operating at 15 GHz. Statistics obtained from each distribution are tested against the corresponding ones derived from the experimental data using a test variable described in the ITU recommendation P.311-13 and an alternative test variable.

This contribution outlines a statistical characterization of Brazilian in-home and low-voltage electric energy distribution networks as a data communication medium. The discussions are based on estimated channels obtained in a measurement campaign carried out in several apartments whose size ranges from 50 up to 90 square meters. The parameters considered for this analysis is the root-mean square delay spread (RMS-DS), the average channel gain, and the channel capacity. For the sake of comparison with electric networks in US, the frequency band ranging from 1.705 up to 30 MHz was set. The reported analysis shows that the RMS-DS can be modeled as a log-normal variable in only 33.33% of the cases and the average channel gain does not follow a log-normal distribution, the average channel gain is lower in Brazil than in US and the inter-symbol interference is quite similar in both US and Brazil.

Abstract-The method currently recommended by the ITU-R for the prediction of rain attenuation in terrestrial line-of sight links considers an equivalent path length over which the rain intensity is assumed to be constant. In other methods, the spatial and temporal variations of the rainfall rate along the path are characterized by an effective rainfall rate that is dependent on the actual path length. Based on experimental measurements, this paper presents a modified effective rainfall rate method that includes the prevailing wind direction during rainy conditions as an additional parameter for the prediction of rain attenuation. The wind direction, which can be obtained from meteorological databases with global coverage, is shown to significantly improve prediction accuracy.

This work aim at presenting a preliminary analysis of additive noises on outdoor and low voltage electric power grid when the frequency band between 1.7 and 100 MHz is considered. These noises were obtained during a measurement campaign carried out in a Brazilian suburban area comprising a low-income community. The statistical analysis in the time and frequency domains reveal the hardness of such environment for data communication as well as the white holes that can be opportunistic used by PLC systems to operate in the same frequency band of primary users.

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