ANALYSIS OF MOBILE TELECOMMUNICATION PATH LOSS IN RURAL COMMUNITIES

In this work, a cheaper alternative method of determining path loss using Network cell info lite software is proposed. Hata-Okumura model is used in the determination of path loss and signal strength of mobile communication devices within Ibogun and Ifo, a suburban community in Ogun state, Nigeria. Additionally, this paper is also aimed at determining the path loss under transmission line to ensure proper network planning in areas covered by transmission lines. Result obtained shows that areas with pylons have greater path loss compared to areas with no pylons. It is recommended that the power levels of base station operating in this area should be increased.


INTRODUCTION
Path Loss is the decrease in the power density of an electromagnetic wave between the transmitter and the receiver [1]. Path loss models describe the signal weakening between a transmitting and a receive antenna as a function of the propagation distance and other parameters. Some models include many details of the terrain profile to estimate the signal attenuation, whereas others just consider carrier frequency and distance. The heights of antennas of both base station and mobile receiver are also critical parameters when modelling path loss. In general, the losses present in a signal during propagation from base station to receiver may be classical and already exiting. General classification includes three forms of modelling namely: empirical, semi deterministic, and deterministic models, to analyse these losses [2]. image by using maximum likelihood algorithm (MLA) to identify objects in the area, divided them into grids, and then classify them into different categories i.e. road, plain, building, forest and water in order to determine the type of area of propagation into free space, rural, forest, suburban, urban and dense-urban areas. This was done using fuzzy logic with respect to inputs from the grid categories.
In like manner, authors in [4] investigated the effect of Clutters on Path Loss proposed by W-I Propagation Model. Work done in [4] proposed a modified model of the W-I model by adding the effect of vegetation, sea, snowfall and rain. Accordingly, simulation result was used to illustrate the effect of disorganized obstructions on path loss proposed by W-I propagation model. Several models have been developed to determine path loss but none of these models have been able to address all the challenges of accurately modelling all the loss component of an electromagnetic signal. Example of these models include: Egli model which was derived from real-world data on ultra-high frequency (UHF) and very high frequency (VHF) television transmissions in several large cities, and it predicts the path loss for a point-to-point link. The Hata-Okumura model on the other hand was built using data collected in the city. Accordingly, this model is ideal for use in cities with many urban structures. Authors in [5] modelled signal propagation considering highly obstructed and less obstructed areas using a mobile signal analyzer. Result obtained in [5] showed that the network that uses higher effective isotropic radiated power (EIRP) value of 64.5 dBm with lower antenna gain of 17.5 dB covered more distance up to 3000 m from the BS transmitter before fading below -100 dB compared to the network that uses lower EIRP of 64.00 dBm and higher gain of 18dB, which faded faster below -100 dBm from distance of 2250 m.
Authors in [6] investigated the optimized path loss model for the effects of environmental factors on mobile signal strength. Result obtained in [6] show that incorporating environmental parameters has the potential to give accurate path loss predictions. Other models include: Okumura-Hata model which is used to predict the path loss of cellular transmissions in exterior environments [7,8]. Lee Model which is a relatively simple, intuitive model which provides reasonably accurate path loss predictions, and Walfisch-Ikegami model which facilitates radio frequency path loss predictions in typical sub-urban and urban environments [7].
In contrast to existing results, this work proposes a cheaper alternative method of determining path loss using Network-cell-info-lite software. In particular, Hata-Okumura model is used in the determination of path-loss and signal strength of mobile communication devices within Ibogun and Ifo Community (a rural community in Ogun state, Nigeria - Figure 1). Additionally, this paper considers the determination of path loss under transmission line to ensure proper network planning in areas covered by transmission lines. This is because several communities in Lagos and other parts of Nigeria are criss-crossed by Pylon (transmission line).

EXPERIMENTAL SET UP
The area covered in this work is the Olabisi Onabanjo University, Ibogun Campus, Ibogun, Ogun state, Nigeria. We investigate the received mobile signal measurements and data collection at the cellular mobile fields of the two mobile service networks available in Ibogun community. The received signal power density is measured and collected with the use of a cellular mobile network analyser named Network-cell-info-lite which is capable of measuring signal power density in decibel milli watts (dBm).
Some selected buildings such as the Electrical, Computer, Mechanical, Civil engineering buildings as well as selected houses within Ibogun campus were considered while taking the drive test.

Experimental Measurements
Experimental measurements were obtained at designated locations with the use of a mobile application (Network-Cell-Info-Lite) capable of measuring received signal power in decibel milliwatts (dBm). During measurements, readings of received signal powers were taken as the motorcycle moved away from the serving base stations. The first reading was carried out at Ifo road to Ibogun with the mobile software, and measurements such as the received signal, height, longitude, latitude and some other relevant values were recorded. The Hata-Okumura model includes adjustments to the basic equation to account for Urban, Suburban and Open area propagation losses (eq. 1 -4).

Results
The values of simulated path-loss/experimental path-loss atc1920-1955 MHz/1835-1850 MHz in a sub-urban area are given in the Tables 1 -2. The simulated/experimental path-loss under transmission line are given in the Table 3.

CONCLUSION
The studies compared simulated and experimental result for path loss in areas where there are no pylons with areas where there are pylons. This studies shows that areas with pylons have greater path loss compared with areas with no pylons. It is therefore recommended that power levels of base station operating in this area should be increased. This can be done using antenna with higher gain. Conclusively, this study show that there is a need to consider the atmospheric factor in propagation prediction models in order to achieve effective planning of cellular networks of next generation communication systems.