Bexhet Kamo

A Method of GSM Antenna Modeling for the Evaluation of the Exposed Field in the Vicinity

In this work, a simple, accurate and very efficient method for the evaluation of the field in the vicinity of GSM antennas of the base-station (BS) in urban areas is presented. The method is based on the replacement of the antenna panel with a group of discrete source emitters. Also, a geometrical approximation is used for the evaluation of the environments influence. The approximate results are compared with the results taken from the use of NARDA SRM 3000 measuring equipment. The presented method could be successfully used for the exposure evaluation of the electromagnetic (EM) field emitted by GSM antennas of the base-station in urban areas.

A Fuzzy-Based Simulation System for Cluster-Head Selection and Sensor Speed Control in Wireless Sensor Networks

Cluster formation and cluster head selection are important problems in sensor network applications and can drastically affect the networks communication energy dissipation. However, selecting the cluster head is not easy in different environments which may have different characteristics. In order to deal with this problem, we have proposed a system for controlling sensor speed in Wireless Sensor Networks (WSNs). The proposed system is based on fuzzy logic. We use 4 input linguistic parameters: Remaining Power of Sensor (RPS), Degree of Number of Neighbor Nodes (D3N), Distance from Cluster Centroid (DCC) and Sensor Speed (SS) for selection of the cluster-head and the control of sensor speed. By controlling the sensor speed, we are able to predict whether the node will leave or stay in the cluster. We evaluate the proposed system by simulations and show that the system has a good behavior.

Elevation impact on signal to spectral noise density ratio for Low Earth Orbiting satellite ground station at S-band

Ground stations are part of any satellite network, providing communication with satellites. Low Earth Orbit (LEO) satellites are used for public communication and for scientific purposes. The communication quality depends on the performance of the satellite ground station, in addition to that of the satellite. Usually, LEO satellites communicate with ground stations at S-band. Ground stations can communicate with LEO satellites only when the satellite is in their visibility region. The duration of the visibility and so the communication duration vary for each LEO satellite pass over the ground station, since LEO satellites move too fast over the Earth. The range over the same satellite path depends on the look elevation angle from the ground station. The shortest range is achieved under maximal elevation of satellites path above the ground station. The range variation causes the free space loss changes impacting on link budget. For the downlink performance, of the greatest interest is receiving system signal to noise ratio (S/N) or (S/N0). (S/N) depends on the last end receiving device bandwidth. In order to avoid the effect of the last end receiving device bandwidth, within this paper only the impact of elevation on signal to spectral noise density ratio (S/N0) is considered.

An algorithm for processing the measurement results of electromagnetic field near 2G and 3G base stations in Albanian territory

The 3G mobile services are usually accomplished by implementation of multiband antennas at 900 MHz, 1800MHz and 2100MHz. Multiband antennas enable simultaneous services at these three frequency bands, and consequently the higher emitted power density. Within the vicinity of these antennas it is of interest the non ionizing radiation level to be measured for each frequency, then for three frequencies and finally the total radiation as results of other active contributors that are too close with the location under the observation. Applied measurement tools and methods will generate relatively a large amount of data that need to be processed and interpreted. Measurements are taken in 80 mobile stations distributed all over Albanian territory. The proposed algorithm applied for processing, visualizing and interpreting the measurement results of non ionizing radiation is given through this paper. The proposed algorithm tends to give in a shorter time results of processing the measurements. The comparison of measured values with maximum estimated values, of non ionizing radiation, is another argument of this paper.

Performance Analysis of Multicast Routing Protocols MAODV, ODMRP and ADMR for MANETs

A Mobile Ad hoc Network (MANET) is a collection of wireless mobile terminals that are able to dynamically form a temporary network without any aid from fixed infrastructure or centralized administration. In recent years, MANETs are continuing to attract the attention for their potential use in several fields such as military activities, rescue operations and time-critical applications. A very important and necessary issue for mobile ad hoc networks is to finding the root between source and destination that is a major technical challenge due to the dynamic topology of the network. Routing protocols for MANETs could be differ depending on the application and network architecture. The efficiency of the wireless link can be increased by multicasting through sending single copy of messages to all group members. Multicast transmission is a more effective mechanism when compared to unicasting in supporting group communication applications and hence is an important aspect of future network development. This paper evaluates the performance of three multicast routing protocols for MANETs, notably MAODV, ODMRP and ADMR. Different performance aspects are investigated including, throughput, link delay, transmission and control overhead.

The Coverage Analysis for Low Earth Orbiting Satellites at Low Elevation

Low Earth Orbit (LEO) satellites are used for public networking and for scientific purposes. Communication via satellite begins when the satellite is positioned in its orbital position. Ground stations can communicate with LEO satellites only when the satellite is in their visibility region. The duration of the visibility and the communication vary for each LEO satellite pass over the station, since LEO satellites move too fast over the Earth. The satellite coverage area is defined as a region of the Earth where the satellite is seen at a minimum predefined elevation angle. The satellites coverage area on the Earth depends on orbital parameters. The communication under low elevation angles can be hindered by natural barriers. For safe communication and for savings within a link budget, the coverage under too low elevation is not always provided. LEO satellites organized in constellations act as a convenient network solution for real time global coverage. Global coverage model is in fact the complementary networking process of individual satellites coverage. Satellite coverage strongly depends on elevation angle. To conclude about the coverage variation for low orbiting satellites at low elevation up to 10o, the simulation for attitudes from 600km to 1200km is presented through this paper. Keywords—LEO; satellite; coverage

The Range and Horizon Plane Simulation for Ground Stations of Low Earth Orbiting (LEO) Satellites

Communication via satellite begins when the satellite is positioned in the desired orbital position. Ground stations can communicate with LEO (Low Earth Orbiting) satellites only when the satellite is in their visibility region. The ground station’s ideal horizon plane is in fact the visibility region under 0˚ of elevation angle. Because of natural barriers or too high buildings in urban areas, practical (visible) horizon plane differs from the ideal one. The duration of the visibility and so the communication duration varies for each LEO satellite pass at the ground station, since LEO satellites move too fast over the Earth. The range between the ground station and the LEO satellite depends on maximal elevation of satellite’s path above the ground station. The dimension of the horizon plane depends on satellite’s orbital attitude. The range variations between the ground station and the satellite, and then ground station horizon plane simulation for low Earth orbiting satellites as a function of orbital attitude is presented. The range impact and horizon plane variations on communication duration between the ground station and LEO satellites are given.

Poster: Downlink free space loss compensation through receiver bandwidth selectivity at LEO satellite ground stations

Low Earth Orbit (LEO) satellites are used for public networking and for scientific purposes. Communication via satellite begins when the satellite is positioned in its orbital position. Ground stations can communicate with LEO satellites only when the satellite is in their visibility region, since LEO satellites move too fast relative to a fixed point (ground station) on the Earth. The major loss in communication between the LEO satellite and the ground station is the free space loss. Free space loss varies since the distance from the ground station to the satellite varies over time. Free space loss is usually compensated through variable satellite transmit power on the downlink. This paper tries another approach on free space loss compensation, through receiver bandwidth adjustability at the ground station, in order to obtain the constant margin at the receiver. For analytical and simulation purposes, the altitudes from 600km to 1200km are considered.

Low cost QoS and RF power measuring tool for 2G/3G mobile network using Android OS platform

The proliferation of corporate and end user mobile internet services offered for smartphones and tablets, makes it necessary to monitor the quality of service and experience provided by mobile internet service providers. In this context, we introduce a low cost tool for monitoring network parameters as received signal power and network responding time. The application is used for signal and latency monitoring for fast and slow moving users in a surveyed area especially for in car communication. The developed application can be useful for mobile operators in order to improve their network quality as well as for end users who can get an insight into the quality of service offered by their service provider. In the proposed application, two software tools are used; first, the capabilities of the android programming interface and second the PHP scripting for measured data post-processing and reporting on web servers. The application is currently tested in Tirana, Albania for evaluating the network parameters of mobile providers showing that only monitoring the received signal power level is not sufficient for assuming a good quality of service.

Modeling of Radio Base Stations with the Numerical FDTD Method, for the Electromagnetic Field Evaluation

Settling down an efficient and reliable procedure for the evaluation of the EMF exposure, from the Base Station Antennas, is important for mobile communications. In this work a calculation method of the exposure under radiofrequency, due to the presence of some antennas of the cellular Base Stations is introduced. The model of wave diffusion in free space, under ideal conditions gives ground for a convenient calculation of the exposure, even in cases of a considerable distance from the antenna, whose covering area is considerably larger, thus resulting in overestimation of the exposure. The calculation of the electrical intensity of the radiation is possible when the technical specifications of the given antenna (provided by the manufacturer) are known and by defining the position of the given point in relation to the antenna.