Enhanced bidirectional authentication scheme for RFID communications in Internet of Things environment

Among the security issues in the environment of the Internet of things (IOT), the security of information source is a privilege to be concerned. To protect data collection and control devices in IOT, first of all, ones shall ensure the authenticity of information source. To address the uncertainty problem of information sources in IOT, identity authentication technology is essential. In this study, we suggested an enhanced bidirectional authentication scheme that is suitable for Radio Frequency Identification (RFID) communications among devices or between devices and control devices in an IOT environment. Specific improvement measures included three aspects: back-up terminals, a condition monitoring device to increase authentication properties, and an alarm mechanism. The enhanced bidirectional authentication protocol presented in this article has the characteristics of excellent performance in security and privacy protection, which could authenticate data contents, even positions and other data properties, and resist the replay or denial of service attacks; at the same time, it could overcome the defect of data asynchrony between the front end and the back end, providing users with excellent forward security. The simulation experiments showed that system reliability was greatly enhanced by adopting the proposed protocol

Heterogeneous Wireless Networks: Traffic Offloading, Resource Allocation and Coverage Analysis

Unlike 2G systems where the radius of macro base station (MBS) could reach several kilometers, the cell radius of LTE-Advanced and next generation wireless networks (NGWNs) such as 5G networks would be random and up to a few hundred meters in order to overcome the radio signal propagation impairments. Heterogeneous wireless networks (HetNets) are becoming an integral part of the NGWNs especially 5G networks, where small cell base stations (SBSs), wireless-fidelity (WiFi) access points (APs), cellular BSs and device-to-device (D2D) enabled links coexist together. HetNets represent novel approaches for the mobile data offloading, resource allocation and coverage probability problems that help to optimize the network traffic. However, heterogeneity and interworking among different radio access technologies bring new challenges such as bandwidth resource allocation, user/cell association, traffic offloading based on the user activity and coverage probability in HetNets. This dissertation attempts to address three key research areas: traffic offloading, bandwidth resource allocation and coverage probability problems in HetNets. In the first part of this dissertation, we derive the mathematical framework to calculate the required active user population factor (AUPF) of small cells based on the probabilistic traffic models. The number of total mobile users and number of active mobile users have different probabilistic distributions such as different combinations of Binomial and Poisson distributions. Furthermore, AUPF is utilized to investigate the downlink BS and backhaul power consumption of HetNets. In the second part, we investigate two different traffic offloading (TO) schemes (a) Path loss (PL) and (b) Signal-to-Interference ratio (SIR) based strategies. In this context, a comparative study on two techniques to offload the traffic from macrocell to small cell is studied. Additionally, the AUPF, small cell access scheme and traffic type are included into a PL based TO strategy to minimize the congested macrocell traffic. In the third part, the joint user assignment and bandwidth resource allocation problem is formulated as a mixed integer non-linear programming (MINLP). Due to its intractability and computational complexity, the MINLP problem is transformed into a convex optimization problem via a binary variable relaxation approach. Based on the mathematical analysis of the problem, a heuristic algorithm for joint user assignment and bandwidth allocation is presented. The proposed solution achieves a near optimal user assignment and bandwidth allocation at reduced computational complexity. Lastly, we investigate the transition between traditional hexagonal BS deployment to random BS placement in HetNets. Independent Poisson Point Processes (PPPs) are used to model the random locations of BSs. Lloyds algorithm is investigated for analyzing the coverage probability in a network which functions as a bridge between random and structural BS deployments. The link distance distribution is obtained by using the Expectation-Maximization (EM) algorithm which is further utilized for calculating the coverage probability

Traffic-Driven Energy Efficient Operational Mechanisms in Cellular Access Networks

Recent explosive growth in mobile data traffic is increasing energy consumption in cellular networks at an incredible rate. Moreover, as a direct result of the conventional static network provisioning approach, a significant amount of electrical energy is being wasted in the existing networks. Therefore, in recent time, the issue of designing energy efficient cellular networks has drawn significant attention, which is also the foremost motivation behind this research. The proposed research is particularly focused on the design of self-organizing type traffic-sensitive dynamic network reconfiguring mechanisms for energy efficiency in cellular systems. Under the proposed techniques, radio access networks (RANs) are adaptively reconfigured using less equipment leading to reduced energy utilization. Several energy efficient cellular network frameworks by employing inter-base station (BS) cooperation in RANs are proposed. Under these frameworks, based on the instantaneous traffic demand, BSs are dynamically switched between active and sleep modes by redistributing traffic among them and thus, energy savings is achieved. The focus is then extended to exploiting the availability of multiple cellular networks for extracting energy savings through inter-RAN cooperation. Mathematical models for both of these single-RAN and multi-RAN cooperation mechanisms are also formulated. An alternative energy saving technique using dynamic sectorization (DS) under which some of the sectors in the underutilized BSs are turned into sleep mode is also proposed. Algorithms for both the distributed and the centralized implementations are developed. Finally, a two-dimensional energy efficient network provisioning mechanism is proposed by jointly applying both the DS and the dynamic BS switching. Extensive simulations are carried out, which demonstrate the capability of the proposed mechanisms in substantially enhancing the energy efficiency of cellular networks

Analysis and improvement of medium access control protocols in wireless networks. Performance modelling and Quality-of-Service enhancement of IEEE 802.11e MAC in wireless local area networks under heterogeneous multimedia traffic.

In order to efficiently utilize the scarce wireless resource as well as keep up with the ever-increasing demand for Quality-of-Service (QoS) of multimedia applications, wireless networks are undergoing rapid development and dramatic changes in the underlying technologies and protocols. The Medium Access Control (MAC) protocol, which coordinates the channel access and data transmission of wireless stations, plays a pivotal role in wireless networks. Performance modelling and analysis has been and continues to be of great theoretical and practical importance in the design and development of wireless networks. This research is devoted to developing efficient and cost-effective analytical tools for the performance analysis and enhancement of MAC protocols in Wireless Local Area Networks (WLANs) under heterogeneous multimedia traffic. To support the MAC-layer QoS in WLANs, the IEEE 802.11e Enhanced Distributed Channel Access (EDCA) protocol has proposed three QoS differentiation schemes in terms of Arbitrary Inter-Frame Space (AIFS), Contention Window (CW), and Transmission Opportunity (TXOP). This research starts with the development of new analytical models for the TXOP scheme specified in the EDCA protocol under Poisson traffic. A dynamic TXOP scheme is then proposed to adjust the TXOP limits according to the status of the transmission queue. Theoretical analysis and simulation experiments show that the proposed dynamic scheme largely improves the performance of TXOP. To evaluate the TXOP scheme in the presence of ii heterogeneous traffic, a versatile analytical model is developed to capture the traffic heterogeneity and model the features of burst transmission. The performance results highlight the importance of taking into account the heterogeneous traffic for the accurate evaluation of the TXOP scheme in wireless multimedia networks. To obtain a thorough and deep understanding of the performance attributes of the EDCA protocol, a comprehensive analytical model is then proposed to accommodate the integration of the three QoS schemes of EDCA in terms of AIFS, CW, and TXOP under Poisson traffic. The performance results show that the TXOP scheme can not only support service differentiation but also improve the network performance, whereas the AIFS and CW schemes provide QoS differentiation only. Moreover, the results demonstrate that the MAC buffer size has considerable impact on the QoS performance of EDCA under Poisson traffic. To investigate the performance of EDCA in wireless multimedia networks, an analytical model is further developed for EDCA under heterogeneous traffic. The performance results demonstrate the significant effects of heterogeneous traffic on the total delay and frame losses of EDCA with different buffer sizes. Finally, an efficient admission control scheme is presented for the IEEE 802.11e WLANs based on analytical modelling and a game-theoretical approach. The admission control scheme can maintain the system operation at an optimal point where the utility of the Access Point (AP) is maximized with the QoS constraints of various users

A Modelling Framework for Common Radio Resource Management in Mobile Communication Systems

Im Rahmen dieser Arbeit wurde ein Modellierungsframework für die Untersuchung der technologieübergreifenden Verwaltung von Ressourcen heterogener Funkzugangsnetze (Common Radio Resource Management – CRRM) entwickelt. Die fünf Komponenten Umwelt (ENV), Nutzerendgerät (UE), Funkzugangssystem (RAS), CRRM-Informationsmanager (CRRM-IM) und CRRM-Entscheider (CRRM-D) können für die Gestaltung von zentralen bis dezentralen CRRM-Architekturen kombiniert werden. Sie decken damit ein weites Spektrum an möglichen CRRM-Einsatzszenarien ab. Dabei ermöglicht eine klare Struktur des zugrunde liegenden Modells die einfache Übertragung von Lösungsmethoden aus dem Gebiet der Multikriterienoptimierung. Ein integriertes Kostenmodell ermöglicht eine Kosten-/ Nutzen-Analyse für CRRM-Algorithmen und Architekturen. Die Verwendung eines hybriden Simulationsmodells ermöglicht die einfache Integration analytischer Funkzugangstechnologiemodelle und die Simulation komplexer Szenarien mit geringem Zeit- und Speicherbedarf. Hierbei liefern simulative Teilmodelle zeitgetreu neue Eingabeparameter für analytische Teilmodelle, deren Ausgabeparameter wiederum die Eingabeparameter der simulativen Teilmodelle sind. Nach diesem Modell wurde der auf OMNeT++ basierende diskrete ereignisorientierte Simulator HEKATE entwickelt. Der Simulator erwies sich als geeignet die zeiteffiziente Untersuchung von CRRM-Szenarien für UMTS- und GSM/EGPRS-Funkzugangssysteme durchzuführen.This work presents a modeling framework for the efficient evaluation of Common Radio Resource Management (CRRM). Centralized as well as decentralized scenarios can be clearly defined by five standard components, namely the radio access system (RAS), the environment (ENV), the user equipment (UE), the CRRM information manager (CRRM-IM), and the CRRM decider (CRRM-D). The clarity of the model enables an efficient investigation of CRRM algorithms based on multi-criteria optimization theory. The integrated cost model makes possible a cost-benefit investigation of different CRRM algorithms and architectures. A hybrid simulation model, where a simulation model and an analytical model operate in parallel over time, leads to low time and memory demands even for the simulation of complex scenarios. Additionally it allows for a convenient and straightforward integration of different analytical models for wireless network technologies. A discrete event simulator named HEKATE is based on this hybrid simulation model which has been implemented using OMNeT++. The scope of the proposed framework is demonstrated by the evaluation of realistic CRRM scenarios for UMTS and GSM/EGPRS

User-centric power-friendly quality-based network selection strategy for heterogeneous wireless environments

The ‘Always Best Connected’ vision is built around the scenario of a mobile user seamlessly roaming within a multi-operator multi-technology multi-terminal multi-application multi-user environment supported by the next generation of wireless networks. In this heterogeneous environment, users equipped with multi-mode wireless mobile devices will access rich media services via one or more access networks. All these access networks may differ in terms of technology, coverage range, available bandwidth, operator, monetary cost, energy usage etc. In this context, there is a need for a smart network selection decision to be made, to choose the best available network option to cater for the user’s current application and requirements. The decision is a difficult one, especially given the number and dynamics of the possible input parameters. What parameters are used and how those parameters model the application requirements and user needs is important. Also, game theory approaches can be used to model and analyze the cooperative or competitive interaction between the rational decision makers involved, which are users, seeking to get good service quality at good value prices, and/or the network operators, trying to increase their revenue. This thesis presents the roadmap towards an ‘Always Best Connected’ environment. The proposed solution includes an Adapt-or-Handover solution which makes use of a Signal Strength-based Adaptive Multimedia Delivery mechanism (SAMMy) and a Power-Friendly Access Network Selection Strategy (PoFANS) in order to help the user in taking decisions, and to improve the energy efficiency at the end-user mobile device. A Reputation-based System is proposed, which models the user-network interaction as a repeated cooperative game following the repeated Prisoner’s Dilemma game from Game Theory. It combines reputation-based systems, game theory and a network selection mechanism in order to create a reputation-based heterogeneous environment. In this environment, the users keep track of their individual history with the visited networks. Every time, a user connects to a network the user-network interaction game is played. The outcome of the game is a network reputation factor which reflects the network’s previous behavior in assuring service guarantees to the user. The network reputation factor will impact the decision taken by the user next time, when he/she will have to decide whether to connect or not to that specific network. The performance of the proposed solutions was evaluated through in-depth analysis and both simulation-based and experimental-oriented testing. The results clearly show improved performance of the proposed solutions in comparison with other similar state-of-the-art solutions. An energy consumption study for a Google Nexus One streaming adaptive multimedia was performed, and a comprehensive survey on related Game Theory research are provided as part of the work