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© 2022 IEEE.While reducing traffic congestion and decrease the number of traffic accidents in the intersections, most of the traffic light management approaches cannot adapt well to fast changing traffic dynamics and growing demands of the intersections with modern world developments. To overcome this problem, adaptive traffic controllers are developed, and detectors and sensors are added to systems to enable adoption and dynamism. Recently, reinforcement learning has shown its capability to learn the dynamics of complex environments, such as urban traffic. Although it was studied in single junction systems, one of the problems was the lack of consistency with how the real world system works. Most of the systems assume that the environment is fully observable or actions would be freely executed using simulators. This study aims to merge usefulness of reinforcement learning methods with real-world traffic constraints. Comparative performance evaluations show that the reinforcement learning algorithm (Advantage Actor-Critic (A2C)) converges well while staying stable under changing traffic dynamics.

IEEEIn Wireless Sensor Networks (WSNs), energy-efficiency and reliability are two critical requirements for attaining a long-term stable communication performance. Using error control (EC) methods is a promising technique to improve the reliability of WSNs. EC methods are typically utilized at the network-level, where all sensor nodes use the same EC method. However, improper selection of EC methods on some nodes in the network-level strategy can reduce the energy-efficiency, thus the lifetime of WSNs. In this study, a node-level EC strategy is proposed via mixed-integer programming (MIP) formulations. The MIP model determines the optimum EC method (i.e., automatic repeat request (ARQ), forward error correction (FEC), or hybrid ARQ (HARQ)) for each sensor node to maximize the network lifetime while guaranteeing a pre-determined reliability requirement. Five meta-heuristic approaches are developed to overcome the computational complexity of the MIP model. The performances of the MIP model and meta-heuristic approaches are evaluated for a wide range of parameters such as the number of nodes, network area, packet size, minimum desired reliability criterion, transmission power, and data rate. The results show that the node-level EC strategy provides at least 4.4% prolonged lifetimes and 4.0% better energy-efficiency than the network-level EC strategies. Furthermore, one of the developed meta-heuristic approaches (i.e., extended golden section search) provides lifetimes within a 3.9% neighborhood of the optimal solutions, reducing the solution time of the MIP model by 89.6%.

Kablosuz iletişim ağlanndakİ teknolojik gelişmelerle birlikte etkili hareketli İP mimarilerinin gerekliliği daha da açık ortaya çıkmaktadır. İnternetteki çeşitli taşınabilir araçların kullanımı için hareketli İP mimarilerini mümkün kılmak önemli bir konudur. Günümüzdeki İP tabanlı hareketlilik yönetimi standardı olan Mobile IP hareketli kullanıcılar için kablosuz internet erişimi sağlamaktadır. Mobile IP' nin en önemli özelliği hareketli kullanıcının yer değiştirmesini hücre değişimi algoritması sayesinde desteklemesidir. Hücre değişimi algoritması, hareketli kullanıcı bir ağdan diğer bir ağa hareket ederken internet erişiminin sürekliliği ve bu esnada en az veri kaybı için gereklidir. Bu tez, Mobile IP' nin temel özelliklerine, problemlerine, hareketli kullamcımn hücre değişimi yönetimi ile ilgili gelişmelere ve ilavelere değinmektedir. Hücre değişimi sırasındaki gecikmeyi ve veri kaybını azaltmak için öne sürülen Mobile IP'nin hücre değişimi algoritmalarının anlatımı ve değerlendirilmesi bu tezin özünü oluşturmaktadır. Bu tezde, öne sürülen protokollerin ve bu protokollerin birleşiminin karşılaştırmalı performans değerlendirmesi simülasyonlarla ayrıca sunulmaktadır.Anahtar Kelimeler: Kablosuz İnternet, Hareketlilik Yönetimi, Hücre Değişimi Yönetimi, Mobile IP, Gezgin Servis Kalitesi With recent technological advances in wireless communication networks, the need for an efficient architecture for IP mobility is becoming more apparent. Enabling IP mobility architecture is a significant issue for making use of various portable devices appearing on the Internet. Mobile IP, the current standard for IP based mobility management, is capable of providing wireless Internet access to mobile users. The most important feature of Mobile IP is its ability to support the changing point of attachment of the mobile user by an algorithm known as handover. A handover algorithm is needed to maintain connectivity to the Internet whenever the mobile users move from one subnet to another, while simultaneously providing minimum disruption to ongoing sessions. This thesis gives an overview of Mobile IP, its open issues, some of the subsequent enhancements and extensions related to the handover management problem of the mobile user. Description and evaluation of various handover algorithms for Mobile IP which have been proposed to reduce packet loss and delay during handover constitute the core of the thesis. In this thesis, a comparative performance evaluation of the proposed protocols and the combination of them is also presented through simulations.Keywords: Wireless Internet, Mobility Management, Handover Management, Mobile IP, Mobile QoS 103