Volume 2 Issue 1
Authors: Lutfa Akter; Balasubramaniam Natarajan
Abstract: We consider a multi-channel cognitive radio network (CRN) where multiple secondary users share a single channel and multiple channels are simultaneously used by a single secondary user (SU) to satisfy their rate requirements. In this competitive CRN, our interest is in determining optimal power and rate distribution choices for each SU while maintaining fairness in “quality of experience” across all SUs. Unlike prior approaches that focus on resource allocation based on instantaneous quality of service (QoS), our approach to fairness encompasses both current and prior history of user experience with respect to QoS (collectively referred to as “quality of experience”). Specifically, we quantify user experience over time by introducing dynamic fairness weights for each SU in the resource allocation framework. The dynamics of the weights are governed by social behavioral models. In this paper, we study the effect of Homo Egualis (HE), Homo Parochius (HP) and Homo Reciprocan (HR) models. HE or HR based fairness weights in the resource allocation scheme result in a proportionate resource allocation with respect to users demand. Hence, with respect to unweighted allocation scheme (allocation scheme based on instantaneous QoS), the fairness weights in the resource allocation scheme cause some users to sacrifice resources and some users to gain resources to maintain a balance in allocated resources. HP based fairness weights show that collaboration among users through forming group result to achieve a proportionate resource allocation with respect to demand at least across the users of the collaborating group. Simulation results show that considering dynamic fairness weights in the resource allocation scheme provides a better system level fairness index (based on Jain fairness index [1]) relative to the unweighted allocation scheme.
Keywords: Competitive CRN; Quality of Experience; Fairness; Jain fairness index; Home Egualis; Homo Parochius; Homo Reciprocan
Authors: Antonis M. Hadjiantonis
Abstract: The rapid adoption of the Internet and the ubiquitous coverage of cellular/wireless technologies, all concur to the fusion of networks’ physical boundaries. At the same time, the proliferation of mobile and wireless devices changes our expectations as users, forcing enterprises to rethink their network and device management (NDM) approaches. A major driver is the changing role of the end-user, who is now empowered by multiple devices, each with multiple interfaces. In this context, we view Network and Device Management (NDM) as the melting pot for network operations (network management) and system administration (host management), all taking place over user-owned and controlled devices. Our work contributes to the convergence of NDM with the analysis, design, and implementation of a resource-oriented cloud-based NDM service. For interoperability, we use YANG data modeling language to compose new modules and JSON notation to encode policies. Using a proof-of-concept policy example, we present a prototype implementation on a Linux smartphone and demonstrate how policies achieve data offloading for the benefit of users and operators.
Keywords: Management Framework; YANG; REST; Policies
Authors: Balasubramaniam Natarajan; Kan Chen
Abstract: The open network architecture commonly envisioned for cognitive radio networks (CRNs), while offering flexibility, increases vulnerability from a security standpoint. Therefore, understanding and managing the trade-off between CRN performance and security is critical for practical operation. In this paper, we attempt to design a secure CRN by optimizing the total throughput performance subject to constraints on expected security level. We employ block cipher as the security mechanism, vulnerability level as the security metric, and consider an exponential adversary attack model. In order to balance physical layer security and throughput in CRNs, we propose a security level adjustment (SLA) algorithm based on the idea of water-filling. The SLA algorithm can distribute the optimal security levels as well as the optimal cipher block length for each communication link in the CRN depending on the corresponding channel quality. Simulation results for throughput show that our SLA algorithm outperforms conventional fixed block length cipher.
Keywords: Cognitive Radio Networks; Physical Layer Security; Encryption; Optimization
Authors: Alwi M. Bamhdi; Peter J. B. King
Abstract: Mobile Ad Hoc Networks (MANETs) pose challenges in terms of power control, due to their fixed transmission power, the mobility of nodes and a constantly changing topology. High levels of power are needed in wireless networks, particularly for routing. In order to address this problem, power aware routing protocols have been proposed, with the aim of maximising the lifetime of the network. This paper presents an enhancement to the Ad Hoc On Demand Distance Vector (AODV) protocol, by reducing transmission power, when a large number of other radios are within range. This protocol, called DP-AODV (Dynamic Power AODV) combines the hello packet mechanism and the power control mechanism in order to reduce interference between nodes and increase the throughput in the network, thus reducing the overall power consumption. A performance evaluation of this enhanced protocol is carried out in comparison with three standard routing protocols, Ad Hoc On Demand Distance Vector (AODV), Ad Hoc On Demand Multipath Distance Vector (AOMDV) and Dynamic Source Routing (DSR), using network simulator 2 (NS2).
Keywords: MANET; Dynamic Power; Density; Mobility; Interference
Authors: Pratik Mondal; Hiranmoy Dey; Arabinda Roy; Susanta Kumar Parui
Abstract: A novel concept of bandpass filter (BPF) using distributed stub loaded highpass filter (HPF) and Defected Microstrip Structure (DMS) is proposed in this paper, which exhibits an ultra-wideband (UWB) property. The proposed design exhibits a bandpass response with WLAN rejection by combining the proposed DMS with the highpass filter design approach, also miniaturization is proposed to minimize the structure resulting in the pass band enhancement of the proposed filter with minimum insertion loss. The design consists of shorted stub microstrip transmission line on a substrate with relative dielectric constant 4.4 and thickness 1.59 mm. Its excellent bandpass property is verified by both simulated and measured results which show a result of 90.39% Fractional Bandwidth (FBW). The proposed UWB- BPF has an advantage of compact size, low cost and easy fabrication.
Keywords: Bandpass Filter; Highpass Filter; Defected Microstrip Structure; Ultra-Wideband Filter; WLAN Rejection