Vladi Koliçi

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Remo Caponi

University of Cologne

S. Sadi SEFEROGLU

Hacettepe University

Hend Dawood

Cairo University

Stuart Peel

Curtin University

Raghu Vamsi Potukuchi

Jaypee Institute of Information Technology

Olivier Gaudin

Ecole Nature et Paysage / INSA Centre Val de Loire

Vladimiro Valerio

Dr Yashpal D Netragaonkar

MIT PUNE

ramesh kumar ayyasamy

Universiti Tunku Abdul Rahman

Edriss Titi

Texas A&M University

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Papers by Vladi Koliçi

Application of WMN-HC Web Interface and NS-3 for Optimization and Analysis in WMNs Considering Different Number of Mesh Routers and Architectures

2015 18th International Conference on Network-Based Information Systems, 2015

Wireless Mesh Networks (WMNs) are attracting a lot of attention from wireless network researchers... more Wireless Mesh Networks (WMNs) are attracting a lot of attention from wireless network researchers. Node placement problems have been investigated for a long time in the optimization field due to numerous applications in location science. In this work, we evaluated WMN-HC system which is based on Hill Climbing (HC) to find an optimal location assignment for mesh routers. As evaluation metrics, we used throughput, one-way delay, jitter, fairness index and residual energy. For simulations, we used ns-3 and Optimized Link State Routing (OLSR). We compare the performance of the optimized network topologies by sending multiple constant bit rate flows in the network. The simulation results show that the throughput of 24 mesh routers is higher than other number of mesh routers for both WMN architectures. The delay and jitter of 24 mesh routers is lower than other number of mesh routers. The fairness index of 16 mesh routers is higher than other number of mesh routers for Hybrid WMN architecture. For 16 mesh router, the remaining energy is higher than 24 and 32 mesh routers.

Evaluation of Single-Copy and Multiple-Copy Routing Protocols in a Realistic VDTN Scenario

2016 10th International Conference on Complex, Intelligent, and Software Intensive Systems (CISIS), 2016

In this paper, we evaluate and compare the performance of single-copy and multiple-copy routing p... more In this paper, we evaluate and compare the performance of single-copy and multiple-copy routing protocols in a realistic Vehicular Delay Tolerant Network (VDTN) scenario. The simulations are conducted with the Opportunistic Network Environment (ONE) simulator. The performance is analyzed using delivery probability, overhead ratio, average latency, average number of hops and average buffer time metrics. The simulation results show that multiple-copy protocols perform better in terms of delivery probability compared with singlecopy protocol. The single-copy protocol uses the highest average number of hops and higher average latency compared with multiple-copy protocols. Maxprop achieves the highest delivery ratio and lowest average latency. Spray and wait results are the lowest for overhead ratio, but the longest for average buffer time. First contact have a short buffer time, but it uses a big number of hops.

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

2016 19th International Conference on Network-Based Information Systems (NBiS), 2016

In this paper, we evaluate and compare the performance of four different routing protocols in a m... more 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.

Performance Comparison of Different Routing Protocols in Sparse and Dense VDTNs

2016 IEEE 30th International Conference on Advanced Information Networking and Applications (AINA), 2016

In this work, we evaluate the performance of three routing protocols epidemic, spray and wait and... more In this work, we evaluate the performance of three routing protocols epidemic, spray and wait and maxprop in Vehicular Delay Tolerant Networks (VDTNs). We study the impact of vehicles density and ttl on the network performance. The simulations are conducted with the Opportunistic Network Environment (ONE) simulator. The performance is analyzed using delivery probability, overhead ratio, average latencyand average number of hops metrics. The simulation resultsshow that the increase of node density improves the networkperformance. In dense network scenario, the performance ofepidemic and maxprop routing protocols is better because thenumber of opportunistic contacts between nodes increases. Forsprayandwait the performance is not improved since it uses amaximum of two hops to deliver bundles. Hence, in densenetworks, a bundle may have a significant delay because itcan only be delivered when a relay or source node have andopportunistic contact with the destination. The increase of ttlfrom 30 to 120 min does not improve the performance of threerouting protocols in both scenarios.

Application of WMN-SA Web Interface and NS-3 for Optimization and Analysis in WMNs Considering Different Number of Mesh Routers and Architectures

2015 International Conference on Intelligent Networking and Collaborative Systems, 2015

Wireless Mesh Networks (WMNs) are attracting a lot of attention from wireless network researchers... more Wireless Mesh Networks (WMNs) are attracting a lot of attention from wireless network researchers. Node placement problems have been investigated for a long time in the optimization field due to numerous applications in location science. In this work, we evaluated WMN-SA system which is based on Simulated Annealing (SA) to find an optimal location assignment for mesh routers. As evaluation metrics, we used throughput, one-way delay, jitter, fairness index and residual energy. For simulations, we used ns-3 and Optimized Link State Routing (OLSR). We compare the performance of the optimized network topologies by sending multiple constant bit rate flows in the network. The simulation results show that the throughput is almost the same for both WMN architectures. The delay, jitter and fairness index of 32 mesh routers is higher than other number of mesh routers for I/B WMN architecture. For 16 mesh router, the remaining energy is higher than 24 and 32 mesh routers.

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

International Journal of Web and Grid Services, 2015

In this work, we present WMN-HC and WMN-SA systems which are based on Hill Climbing HC and Simula... more 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.

Analysis of Node Placement in Wireless Mesh Networks Using Friedman Test: A Comparison Study for Genetic Algorithms and Hill Climbing

2015 Ninth International Conference on Complex, Intelligent, and Software Intensive Systems, 2015

In this paper, we deal with connectivity and coverage problem in Wireless Mesh Networks (WMNs). W... more In this paper, we deal with connectivity and coverage problem in Wireless Mesh Networks (WMNs). We used Friedman test to check if we can compare Tabu Search (TS) and Hill Climbing (HC). We found out that TS and HC have differences in their performance. Then, we used the implemented systems WMN-TS and WMN-HC to evaluate and compare the performance of the systems for different distributions of mesh clients in terms of Size of Giant Component (SGC) and Number of Covered Mesh Clients (NCMC). The simulation results show that for Uniform distribution, for small radius of communication distance, the SGC of WMN-TS is better than WMN-HC. For Normal distribution, the WMN-HC performs better than WMN-TS. For Exponential distribution, the WMN-HC performs better than WMN-TS for all radius of communication distances. For Weibull distribution, the WMN-HC has a good performance for big radius of communication distance.

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

2015 Ninth International Conference on Complex, Intelligent, and Software Intensive Systems, 2015

Finding an optimal solution is computationally hard for most combinatorial optimization problems.... more 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.

Analysis of WMN-HC Simulation System Data Using Friedman Test

2015 Ninth International Conference on Complex, Intelligent, and Software Intensive Systems, 2015

With the fast development of wireless technologies, Wireless Mesh Networks (WMNs) are becoming an... more With the fast development of wireless technologies, Wireless Mesh Networks (WMNs) are becoming an important networking infrastructure due to their low cost and increased high speed wireless Internet connectivity. In this paper, we used our proposed and implemented system based on Hill Climbing algorithm, called WMN-HC for mesh router node placement in WMNs. We analyze WMN-HC simulation system data for different number of nodes using Friedman test. We took into consideration 8, 16, 32, 64, 128 mesh routers and 24, 48, 96, 192, 384 mesh clients. We use Size of Giant Component (SGC) and Number of Covered Mesh Clients (NCMC) as metrics. From the analysis, for all cases, the p-value of SGC is more than 0.05. Thus, we adopt H0. On the other hand, for NCMC, we adopt H1 because the p-value is less than 0.05. Friedman test results show that there is not difference for SGC parameter. However, there is difference for NCMC parameter.

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