Radio Refractivity Study in Akure-Owo Digital Microwave Link in South Western Nigeria

This work is a study of radio refractivity in Akure-Owo Digital Microwave Link in South Western Nigeria. Meteorological data of air temperature, atmospheric pressure, relative humidity, and water vapour pressure were measured between January and December 2006 at the observatory centre of the Nigerian meteorological agency (NIMET) situated at Akure Airport. The meteorological data collected were computed to obtain the refractivity, refractivity gradient and earth radius factor. The results of the study show that the refractivity gradient was greater than zero and vary slightly throughout the months of the year 2006. The highest value of refractivity gradient was in April and lowest value in September, the effective earth radius factor was observed to be less than one which implies that there is sub-refraction in the link. Sub refraction is a situation in which the radio signal beam is refracted upwards in the link thereby resulting in microwave link loss.http://dx.doi.org/10.4314/njt.v34i3.2

Design of a GSM phone booth for low cost rural communication

The GSM phone booth was designed as a mobile phone with solar arrays on the roof. These arrays are for charging the phone batteries and powering the booth during the day while the batteries which can be bigger, powers the phone at night or in the absence of sunlight. The cell phone platform was integrated into the booth such that when a SIM card is inserted it can be used as if it were a personal phone. The SIM card holder was designed in such a way that the user carries it along to the phone booth and slots it into the provided slot on the booth before making a call. It was also designed to switch on or off the phone booth such that when the card is removed the booth is switched off while the battery continues to charge. This is another mean by which the battery life is extended. The design provides a low cost approach for extending mobile communication to rural areas and also for campuses and public area

Rural Mobile Telephony: A VSAT (Satellite) based Approach

This work presents a VSAT based approach for extending mobile communication access to rural communities in developing countries using VSAT and satellite technology. The rural areas are clustered into village community cells with each cluster being served by a non regenerative bidirectional repeater system. The telecommunication technology of choice is the GSM standard. Traffic from the rural areas is collated together at the access point which serves as an interface between the village community cells and the satellite. The access points perform a frequency translation moving the signal from the GSM band to the satellite band at the transmitter and vice versa at the receiver. The system maximizes the advantage of satellite communication technology over other types in linking remote areas to urban centers that are geographically far apart. The satellite then links the village cell to the operator’s network via a dedicated BTS in the urban area. The system has the advantage of being modular, scalable and solar powered due to the low traffic from rural areas

Traffic Modeling in Mobile Communication Networks

This paper is focused on traffic modeling in Mobile Communication networks. This research is aimed at developing a traffic model that will predict a blocking probability for voice calls and handover calls blocking probability in mobile communication networks (GSM). The high number of block calls experience in mobile network, especially during the busy- hour as leads to poor Quality of Service (QOS) delivering in mobile network. The block calls experience in mobile network should be reduced (in line with NCC recommended value 2%) to a certain low values, to ensure good QOS. The developed traffic model is focused on new voice calls and handover calls in a cell. The developed traffic models are designed based on the number of channels resource available; these numbers of channels are partition into two segments in a cell network. The cell technology is homogenous in nature; therefore it is applicable to the entire mobile communication system. The analytical method is deployed, and the collection traffic data with equipment know as the Operation and Maintenance Center (OMC-counter) which is in built in the mobile communication network. The OMC-counter runs on Linux operation software, which helps to capture the number of arrival calls and service time in a specified interval. The arrival rate is assumed to be Poisson and the interarrival rate (the different between two arrival points or more) is also, assumed to be exponentially distributed and independence identical distributed. These parameters were assumed in the developed traffic model. The developed traffic models are blocking probability for voice calls and handover calls are shown in Equation (3) and (4). These traffic models are used to manage, a balance relationship between cost incurred in mobile communication by operators and service render to the mobile subscribers. Keywords: Arrival rate, service time, exponential distribution, channels rate and traffic load in erlang

Distal systems in topological dynamics and ergodic theory

We generalize a result of Lindenstrauss on the interplay between measurable and topological dynamics which shows that every separable ergodic measurably distal dynamical system has a minimal distal model. We show that such a model can, in fact, be chosen completely canonically. The construction is performed by going through the Furstenberg--Zimmer tower of a measurably distal system and showing that at each step, there is a simple and canonical distal minimal model. This hinges on a new characterization of isometric extensions in topological dynamics

Analysis and Development of a Low Cost GSM Telephone System for a Rural Area

This work presents the analysis and development of a low cost GSM telephone system. A review of radio receiver and·transmitter architectures showed the superheterodyne as having a better performance over the direct conversion radio in terms of selectivity and complexitY.. A low power bidirectional transceiver was developed based on the superheterodyne architecture. The specifications of the bidirectional transceiver were computed using specifications of the component modules in the spreadsheet approach. The resulting design was optimized using Matlab programs and simulated using the Genesys simulation software. The results show the front end of the transceiver as the most critical part of the transceiver. Both the generic and proposed transceivers had frequency response from 1700MHz to 1900MHz, the same dynamic range and noise figure but the proposed transceiver achieved these results with a 50% reduction in power amplifier and low noise amplifier chi!JS and the 75% reduction in the number of voltage oscillator chips. This reduction in component count fed to a 40.59% reduction in power requirement and a reduction in the overall cost of the proposed transceiver. The reduced power consumption of the architecture enables the use of solar energy as an alternative source of power supply for the transceivers

A critical examination of the impact of armed conflict on children: A case study of Uganda

Conflict and violence are as old as life itself. Violence has always been and continues to be an instrument of power, maintaining the status quo between the victor and the vanquished. As unfolding events point to the fact that power and money rule the world creating new conflicts, tension and violence, it is difficult to imagine a world without wars. Armed conflict exists, when there is resort to arms by warring states or protracted armed violence, between such groups within a state. Socio-politically, armed conflict can be defined as conflicts or war between population groups, geographic units, political parties, religious and economic classes. During such armed conflicts, atrocities are committed, rights are violated and treaties breached. In all these, women and children seem to be disproportionately affected. This paper seeks, using the doctrinal method and written works on the issue, to identify and x-ray the impact of armed conflict on children with special reference to Uganda.Keywords: Armed conflict, Children, Uganda, Human Right