Browsing by Author "Rahel, Abera"

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    Characterizing and Modeling WAN Egress Traffic
    (AAU, 2018-05) Rahel, Abera; Yalemzewd, Negash (PhD)
    Computer networks exhibit complex characteristics due to the heterogenous nature of traffic running through the network. This makes the design of reliable networks and network services difficult. To have a design of robust and reliable networks, a detailed understanding of traffic characteristics of the network is needed which will lead to distinguish the traffic model it fits. In this paper, it is showed that the WAN egress traffic possess self-similar characteristics, using different mathematical techniques. And also, the presence of long memory in WAN egress traffic is shown by the Autocorrelation Function of the trace. Additionally, it is showed that one of the self-similar long memory models, Fractional Auto-Regressive Integrated Moving Average (FARIMA) model, best capture the collected WAN traffic data. To model the traffic data first stationarity was tested using Augmented Dickey Fuller (ADF) test. The AR and MA terms of the model are estimated using the ACF and PACF plot. To test the model, Autocorrelation function is used, and it is found that the Autocorrelation function of the approximated data has a resemblance to the Autocorrelation function of the collected data.
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    Mobile Enabled Passenger Information System for Addis Ababa Light Rail Transit
    (Addis Ababa University, 2019-06) Rahel, Abera; Mesfin, Kifle (PhD)
    Passenger information system helps to ease the access to the public transport network for each person. Reliable real-time information should be available for passengers before and during travelling time. Providing most appropriate arrival time and train route location from the beginning to the end of their journey is necessary in order to enable passengers to plan door-to-door journey. For the case of Addis Ababa light Rail transit (AALRT) there is travel information for on board passengers, but the service lacks information for passengers who are outside the train, there is no real time information system at all. A Research has been done to solve AALRT information scarcity, information system that will be fixed at stations has been proposed before. But the solution will only be useful for passengers who are waiting at ending stations. Seeing this limitation, this thesis focuses on the passenger information system that will meet the real-time management needs, Real time location that consists on information about what really is happening, regarding the current service being executed. This passenger information system enables passengers to look at availability of train, while at home, in the office, in the hotel or while waiting in a train station, Passengers can see the location of a train on a chosen specific route, the expected time of arrival of the train at stations. Mobile enabled passenger information system that works in three delivery modes is designed; those delivery modes are android app, web and SMS (Short Message Service) provided within GSM network standard. The system needs hardware equipment‘s such as GPS with its receiver, server machine, GSM modems and Android Mobile phones to be implemented. This information system has been simulated successfully using simulation tools such as proteus software with Ardunio and Android studio for designing the Android app.