Algenti Lala

A Fuzzy-Based CAC Scheme for Cellular Networks Considering Security

Call Admission Control (CAC) is one of the resource management functions, which regulates network access to ensure QoS provisioning. However, the decision for CAC is very challenging issue due to user mobility, limited radio spectrum, and multimedia traffic characteristics. In this paper, we propose a new CAC scheme which considers for acceptance decision except other parameters also the security. We call the proposed system FACS-S (Fuzzy Admission Control - with Security). We evaluated by simulations the performance of proposed system and show that the FACS-S has a good behavior.

Application of WMN-SA Simulation System for Node Placement in Wireless Mesh Networks: A Case Study for a Realistic Scenario

One of the key advantages of Wireless Mesh Networks WMNs is their importance for providing cost-efficient broadband connectivity. In WMNs, there are issues for achieving the network connectivity and user coverage, which are related with the node placement problem. In this work, the authors consider the router node placement problem in WMNs. The objective is to find the optimal distribution of router nodes in order to provide the best network connectivity the maximal number of connected routers and coverage maximal number of covered clients. The authors apply their proposed WMN-SA simulation system in a realistic scenario of the distribution of mesh clients considering Itoshima City, Fukuoka Prefecture, Japan. From simulation results, they found many insights that can be very important for real deployment of WMNs.

Clustering Algorithms in MANETs: A Review

A Mobile Ad hoc Network (MANET) is a multihop wireless network in which the mobile nodes are dynamic in nature and has a limited bandwidth and minimum battery power. Due to this challenging environment the mobile nodes can be grouped into clusters to achieve better stability and scalability. Grouping the mobile nodes is called clustering, in which a leader node is elected to manage the entire network. In this paper, we consider the various approaches for clustering focus on different performance metrics. Each cluster contain a particular node called cluster head which is elected as cluster head according to the specific metric or combination of metrics such as mobility, energy, degree, weight etc. In this survey paper, we study some clustering schemes such as Mobility-based clustering, Energy-efficient clustering, Connectivity-based clustering, Weighted-based clustering and discuss their advantages and disadvantages.

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 web interface for wireless mesh networks based on heuristic algorithms: optimisation and analysis for different scenarios

In this work, we present WMN-HC and WMN-SA systems which are based on Hill Climbing HC and Simulated Annealing SA for location assignment of mesh routers in Wireless Mesh Networks WMNs. As evaluation metrics, we used throughput, one-way delay, jitter, fairness index and residual energy. The simulation results show that for WMN-HC, the throughput of 24 mesh routers is good for both WMN architectures. But, for WMN-SA, the throughput is almost the same. For WMN-HC, the delay and jitter of 24 mesh routers is low for both WMN architectures. However, for WMN-SA, the delay and jitter of 32 mesh routers is higher for I/B WMN architecture. For WMN-HC, the fairness index of 16 mesh routers is high for Hybrid WMN architecture. But, for WMN-SA, the fairness index of 32 mesh routers is high for I/B WMN architecture. For 16 and 32 mesh routers, the remaining energy of WMN-HC is higher than WMN-SA.

On Local vs. Population-Based Heuristics for Ground Station Scheduling

Finding an optimal solution is computationally hard for most combinatorial optimization problems. Therefore the use of heuristics methods aims at finding, if not optimal, near optimal solutions in reasonable amount of computation time. Due to lack of knowledge about the landscape of fitness function, searching the solution space by heuristic methods becomes very challenging. One can search the solution space through local search methods that build a path of feasible solutions. Here, the search method selects one solution at each iteration towards reaching the near optimal solution. To this group belong Hill Climbing, Simulated Annealing, Tabu Search and other algorithms. Alternatively, one can use heuristic methods that use many feasible solutions at the same time at any iteration, known as population-based heuristics. In this group there are Genetic Algorithms (GAs and its variants), Memetic Algorithms (MAs), and more generally, Evolutionary Algorithms (EAs). The research issue is, for a given combinatorial optimization problem, which of the two search methods is more effective. This is even more challenging for the case of highly constraint problems. In this paper we present a study on the effectiveness of using local search vs. Population-based search for the problem of Ground Station Scheduling problem, which is known for its high complexity and over-constraint nature.

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.

Evaluation of Different DTN Routing Protocols in an Opportunistic Network Considering Many-to-One Communication Scenario

In this paper, we evaluate and compare the performance of four different routing protocols in a many-to-one communication opportunistic network. Seven groups with three stationary sensor nodes sense the temperature, humidity and wind speed and send these data to a stationary destination node that collect them for statistical and data analysis purposes. Vehicles moving in Tirana city roads during the opportunistic contacts will exchange the sensed data to destination node. The simulations are conducted with the Opportunistic Network Environment (ONE) simulator. For the simulations we considered two different scenarios where the distance of the source nodes from the destination is short and long. The performance is analyzed using delivery probability, overhead ratio, average latency, average number of hops and average buffer time metrics. For both scenarios the effect of increasing ttl is evaluated. The simulation results show that the increase of ttl from 15 min to 60 min slightly effects the performance of all protocols. By increasing the distance between source nodes and destination node, delivery probability is decreased almost10% for all protocols, the overhead for spray and wait does not change, but for other protocols is slightly increased and theaverage number of hops and average latency is increased.

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

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.