Mobile Radio Path Research Articles

Asynchronous Demodulation Method for Four SS Barranged on Frequency Axis in Mobile Radio Path using Hilbert Transform

In this paper, an asynchronous demodulation method for a four-single sideband (SSB) signal arranged on the frequency axis is developed to support burst mode transmission in a mobile radio path and to achieve greater data throughputs. When a reduced pilot carrier is placed at the center of the 4-SSB signal, it is guarded by lower and upper sidebands, that is, this scheme is classified into a tone-in-band (TIB) system. Digital signal processing (DSP) processors are useful for implementing a Hilbert transform. However, we have for a long time neglected introducing it into the demodulation process of SSB signals.

Semi Deterministic Hybrid Model for Path Loss Prediction Improvement

Mobile radio path loss modeling is an important aspect of network planning which ensures an improved quality of service to the subscribers. In this paper, the predictions made by COST 231 Walfisch-Ikegami propagation model to estimate the path loss of the mobile signals are improved by proposing a hybrid model. The modified model combines the deterministic aspects of ray tracing along with statistical processing of the empirical measurements. It includes a loss term computed for multiple reflections by using the method of images. The ten ray urban street canyon model is extended to compute reflections from multiple paths. The deterministic approach is merged with the statistical variations in the original Walfisch-Ikegami model. It consists of modeling the multi screen diffraction loss, roof to street loss and street orientation function by considering the height of the buildings, the separation and the road orientation angle as random variables with Gaussian distribution. The proposed hybrid model is validated by measurements of GSM 900MHz signals collected in Hyderabad city of Southern India. The performance of the proposed model is evaluated in terms of Prediction Error, Root Mean Square Error and other metrics. The results justify the improvement in the path loss prediction of the proposed semi deterministic hybrid model. This could be useful in link budget analysis and deployment of future cellular networks for the specified urban region and similar scenarios.

Estimation of cellular mobile radio planning parameters using a GTD-based model

The performance of a GTD-based path loss prediction technique is compared with experimental measurements of mobile radio path loss in light-urban and urban environments at 465, 851 and 927 MHz. The method, as currently formulated is shown to be capable of predicting the approximately lognormal behaviour and the excess path loss (relative to plane-earth) that are observed experimentally, but to consistently underestimate the path loss variability.

Attenuation and diffraction effects from truck blockage of an 11-GHz line-of-sight microcellular mobile radio path

The blockage effect of a large box truck passing through the line-of-sight path in a typical 11-GHz microcellular mobile communications link was measured. The results show that attenuation and diffraction effects can be significant when the truck is close to the relatively low antenna on the mobile unit. At a distance of 13 ft, this attenuation can be as much as 35 dB, depending on the type of mobile antenna. As the distance between the truck and the mobile increases, the attenuation decreases. At a distance of 140 ft, the attenuation is insignificant. It is shown that attenuations calculated for this path using the unified theory of diffraction agree very well with measured data. On the basis of this agreement, the theory is used to estimate the attenuation caused by truck blockage, as a function of truck distance to the mobile unit, for frequencies between 1 and 40 GHz.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Variability of mobile radio path loss in Auckland at 465 MHz

A series of field trials in Auckland at 465 MHz have confirmed that the variability of mobile radio path loss is approximately normally distributed and can, therefore, be represented by a standard deviation. This standard deviation has been found to be dependent on the mobile terminal's environment and on frequency, but is essentially independent of base-station antenna height and path length. Standard deviations have been measured as 5.2, 4.4, 5.4 and 5.2 dB for rural, suburban, light urban and urban environments, respectively.

Doppler spectrum measurements at 910 MHz over a suburban mobile radio path

Samples of the Doppler spectrum of a 910-MHz signal propagated to a vehicle moving through a suburban mobile radio environment are presented. The multipath nature of the medium is evident in the data. The sharp limit to the width of the RF spectrum previously predicted analytically is demonstrated.