Majid Hatamian

A novel relay selection scheme for multi-user cooperation communications using fuzzy logic

In this paper we propose a novel relay selection method for cooperation communication networks using fuzzy logic. Many efforts have been made in the literature to select the superior relay based on relays SNR/SER and / or relays reputation (in cooperation stimulation methods). We jointly consider four criteria for the process of relay selection, relays SNR/SER, relays reputation, relaying strategy and relay location. We consider the condition in which network users employ different relaying strategies, i.e., some relay nodes employ decode-and-forward strategy, some nodes employ amplify-and-forward strategy, and the other ones employ compress-and-forward strategy. Also, we categorize the network users into LM clusters and take into account the relative distance of potential relay nodes from the source and destination nodes in the process of relay selection. This relative distance has significant impact on the average achievable rate in destination node. Finally, by using a fuzzy logic decision making method, we select the “best relay” based on these four criteria.

C-trust: A trust management system to improve fairness on circular P2P networks

An important issue in Peer-to-Peer networks is to encourage users to share with others as they use the resources of the network. However, some nodes may only consume from users without giving anything in return. To fix this problem, we can incorporate trust management systems with network infrastructures. Current trust managements are usually made for unstructured overlays and have several shortcomings. They are made to be very similar to e-commerce scoring websites which may not be the best design for fairness in P2P networks. Several problems may arise with their designs such as difficulties to provide a complete history of freeloaders or lack of an autonomous removal mechanism in case of severe attacks. In this paper, we argue that such systems can be deployed more efficiently by using a structured paradigm. For this purpose, we propose C-Trust, a trust management system which is focused on fairness for P2P networks. This is done by getting help from current circular structured designs. This method is able to mark freeloaders, identify their severity of abusion and punish them accordingly. We are also able to effectively protect both Seeder-to-Leecher and Leecher-to-Leecher transactions. This feature is specially important for fairness which other trust systems have not considered so far.

Intelligent Automated Intrusion Response System based on fuzzy decision making and risk assessment

The most important aim of Automated Intrusion Response Systems (AIRSs) is selecting responses that impose less cost on the protected system and which are able to neutralize intrusions progress effectively. Cost-sensitive AIRSs use different methods to launch efficient responses. In this regard, risk assessment as a component for assessing intrusion danger on the system is introduced in many papers. However, most available risk assessment methods produce ambiguous results. Fuzzy logic is known as an effective method to be used in the process of risk assessment. This is mainly because fuzzy approach reduces the level of uncertainty of risk factors. To assess risk by fuzzy methods, risk parameters which are extracted from the traffic patterns are used as inputs of fuzzy systems. The aim of this paper is to introduce an AIRS based on fuzzy risk assessment to evaluate the risk of each intrusion in real time and apply a suitable response for protecting web applications. We also introduce a method for applying responses retroactively. The results of applied method show the effective performance of the proposed method in terms of cost-sensitivity and time to response.

Counter attack to free-riders: Filling a security hole in BitTorrent protocol

Peer-to-Peer (P2P) networks are powerful distributed solutions which do not rely on external servers and gather required resources from their users. Therefore, fairness is an important feature for designers of these networks. Prevention of free-riding is a key aspect for fairness. One of the most important file-sharing protocols in P2P is BitTorrent. This protocol is distinguished from other P2P systems for its unique way of uploading process and its novel approach to fairness. For the first time by implementing eminent game theory strategy, “tit-for-tat” for its protocol, BitTorrent made a breakthrough on fairness for P2P networks. However, it did not take long for researchers to find security holes in its approach. It was proven several times that by making specific clients which do not follow BitTorrent algorithms, it is possible to achieve free-riding. In this paper, by making fairness a universal problem we make free-riding a much harder process. This is achieved by changing the role of Tracker from an indexing server to a more intelligent entity which makes the proper decisions based on different situations.

Classification of the liver disorders data using Multi-Layer adaptive Neuro-Fuzzy inference system

The meaning of classification is assigning data into subsets and clusters which are separated and independent. The data of any subsets have the most similarity to each other and the most difference from the other subsets. In this paper, the classification of the liver disorders data is done with using adaptive Neuro-Fuzzy inference system. In this study, the liver disorders data includes medical and physical information of 345 patients is used to show the Multi-Layer ANFIS performance in data classification and clustering. The dataset is selected from the UCI datasets which is a rich source of heart disease, primary tumor, hepatitis and liver disorders datasets.

A centralized evolutionary clustering protocol for wireless sensor networks

The energy of all sensor nodes in wireless sensor networks is limited. For this reason, providing a method of communication between nodes and network administrator to manage energy consumption is crucial. In this paper, a centralized evolutionary clustering protocol for wireless sensor networks is proposed. The proposed protocol selects the appropriate nodes as CHs according to three criteria that ultimately increases the network life time. This paper investigates the genetic algorithm (GA) as a dynamic technique to find optimum CHs. Furthermore, an innovative fitness function is proposed. Each chromosome which minimizes fitness function is selected by base station (BS) and its nodes are introduced to the whole network as proper CHs. Simulation results show that the implementation of the proposed method using GA, has done significant improvement in terms of the number of nodes alive and the network lifetime.

Priority-based congestion control mechanism for wireless sensor networks using fuzzy logic

In this paper, a priority-based congestion control mechanism for wireless sensor networks using fuzzy logic is proposed. The proposed method tries to make a distinction between locally generated data and transit data in such a priority-based mechanism by providing a novel queueing model. Moreover, two parameters are used as the inputs of fuzzy rate controller: congestion score and buffer occupancy which are based on total packet input rate, packet forwarding rate at MAC layer, number of packets in the queue buffer, and total buffer size at node. As soon as the congestion is detected by the proposed congestion score relation, the notification signal is sent to offspring nodes and they regulate their data transmission rate to parent (sink) node. Simulation results clearly show that the implementation of the proposed method using fuzzy logic, has done significant reduction in terms of packet loss rate and end-to-end delay.

A performance comparison of classical PID, Type-1 and Type-2 fuzzy controller in a three tank level control system

This paper investigates the usage of Conventional PID controller, Type-1 and Type-2 fuzzy controller in controlling the liquid level in the three tank level control system. All real systems exhibit non-linear nature, thus conventional controllers are not always able to provide good and accurate results. Fuzzy logic control (FLC) can be used to obtain more precise results. In this paper a model for simulation is designed and all the assumptions are made before the development of the model. Analysis is done through computer simulation using Matlab/Simulink toolbox. Moreover, the behavior of the system in terms of time response (e.g., settling time, a certain rise-time, overshoot, integral of absolute error (IAE) and integral time of absolute error (ITAE) is studied and the results for the case of utilizing FLCs is compared with the case of employing PID controller.