Edgar Lemos Cid

Measurement, Characterization, and Modeling of the Helicopter Satellite Communication Radio Channel

The satellite-to-helicopter radio channel is measured, characterized, analyzed, and modelled. We used a sweep time delay cross correlation sounder operating at 14.25 GHz and actual helicopters for the experiment. From the measurements, signal fading, delay and Doppler spread are estimated. Wideband radio channel results show that the signal delay spread is small enough, so 32 MHz satellite transponders could be used with no need of equalization. We also observed two important propagation impairments on the received signal envelope, both of them caused by the main rotor blades. The first one is the power attenuation produced when the LoS is obstructed by the blades. We demonstrate that this effect could be mitigated by using spatial or polarization diversity technique in the receiver end. The second one is the presence of multipath propagation leading to a power level oscillation dependent on the amplitude of the received multipath components. An UTD-based 3-D ray tracing model was used to conclude that the main multipath components are generated by diffraction on the rotor blade edges.

Wideband Analysis of the Satellite Communication Channel at Ku- and X-Bands

The results of a wideband channel measurement campaign carried at Ku-band and X-band are presented and discussed in this paper. The propagation effects in the satellite-to-mobile radio link due to the environment surrounding the terrestrial terminal have been characterized using a sweep time delay cross-correlation (STDCC) sounder. The campaign was carried out in four different environments: wooded, rural, suburb and urban. From these results, we obtained the root-mean-square delay spread and coherence bandwidth of the radio channel. The low coherence bandwidth values found for urban and suburb environments suggest that channel equalization would be needed for high-data-rate services. The delay spread values for these two environments are also larger than for wooded and rural environments. A detailed analysis of the results shows that three-state semi-Markov narrow-band channel models for satellite communications could be easily extended to wideband.

High speed transmission at 60 GHz for 5G communications

The results of a wideband channel measurement campaign carried out at the 60 GHz band are summarized in this paper. The propagation effects in this 5G radio link have been characterized using a sweep time delay cross-correlation sounder. We analyze the pointing of the on-road horn antenna using an angular scanning with a pan&tilt instrument. From these data, we obtain the root mean square delay spread of the radio channel. The low value found for the root mean square delay spread in this university campus environment suggests that channel equalization would not be needed for high data rate services. In terms of angular scanning, the receiver power is more sensitive to azimuth variations. We conclude that this channel would be a possibility for high speed transmission at long distance in open areas.