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The paper presents a QoS framework for terminals with multi-RAT (multiple radio access technologies) interfaces for heterogeneous network environment. It investigates a QoS provisioning with vertical multi-homing and multistreaming features for 5G heterogeneous networks. The presented enhanced framework for 5G systems leads to better performance opportunities for multimedia services with very high...
Partial discharge (PD) is one of the predominant factors to be controlled to ensure reliability and undisrupted functions of power generators, motors, Gas Insulated Switchgear (GIS) and grid connected power distribution equipment, especially in the future smart grid. The emergence of wireless technology has provided numerous opportunities to optimise remote monitoring and control facilities that can...
Measurements of UHF-TV band spectra and field-strength levels in the pre- and post-analogue switch-off periods in the cities of Thessaloniki and Skopje clearly demonstrate the much reduced spectrum occupancy, the lower signal levels, and the feasibility of digital dividend phase 1 allocations to cellular operators in the 800 MHz band, digital dividend phase 2 allocations in the 700 MHz band, as well...
Spectrum sensing provides detailed information on the occupancy in a given spectrum band. Practical implementations of spectrum sensing techniques are crucial to gaining complete comprehension of their performance and applicability. Hardware limitations significantly impact the performance of the sensing techniques. This paper presents a cyclostationarity based detection testbed, which incorporates...
Spectrum modeling represents an important tool, of the cognitive radio concept. Number of works have focused on developing accurate methods for modeling the spectrum usage in order to provide reliable and efficient assessment of the possible spectrum availabilities. This paper proposes a novel method for modeling of spectrum usage based on classification of measured quantities into multiple levels...
Recent advances in radio environmental mapping enable novel, practical and efficient cognitive radio and dynamic spectrum access solutions. A crucial aspect of such solutions is to ensure the reliability of the constructed Radio Environmental Maps (REMs). Especially important is the accurate and up-to-date Radio Interference Field (RIF) estimation based on distributed spectrum use measurements. This...
The increasing complexity of the future wireless networks leads to the requirement for self-organization. This is true especially in home networking where users are typically not networking professionals and cannot be expected to perform complex optimization and management tasks. In this context, cognitive radio concept combining cross-layer optimization and learning mechanisms is a promising solution...
The different wireless and wired communication technologies are converging towards a heterogeneous communication network, requiring comprehensive resource management. This paper summarizes the development of a reconfigurable mobile multi-interface terminal, enabled with efficient heterogeneous resource management architecture, called RIWCoS. The created terminal prototype is able to perform seamless...
The demand for higher data rates, capacity and better quality-of-service is constantly growing for home networks. Therefore, there is a pressing need for efficient use of wireless network resources. In this context, the application of cognitive radio principles that enable network nodes to characterize their environment and control their resources based on the acquired knowledge, is the prominent...
Policing a wireless network is an evolving and exciting paradigm, specially emphasized with the emergence of cognitive radio networks. The possibility to manage radio resources efficiently and achieve different goals imposed by different stakeholders with dynamically changing policies in a wireless network is the main advantage of the policy based cognitive system. Moreover, the ability to express...
This paper investigates a simple opportunistic resource sharing scheme enhanced with a borrowing concept from a traffic viewpoint. Resources (such as spectrum, channels etc.) are shared between primary and secondary users through a centralized scheme deployed at a base station. The primary users have the preemptive channel access, whereas the secondary ones opportunistically use the available channels...
Spectrum sensing is an important consideration in the future cognitive radio networks. In order to protect communicating users, it is essential to make a reliable and correct occupancy decision. A possible way in providing a more accurate sensing measurement is to adapt measurement parameters to the inspected band and inspected signal. Parameters settings for resolution bandwidth and sweep time are...
Convergence of different wireless access networks and development towards 4G yields a necessity for more efficient resource management procedures in the integrated heterogeneous platform. The notion of resource is fundamentally different in heterogeneous environments (compared to homogeneous ones) as it is spanned across several different wireless solutions. This paper summarizes the development process...
The concept of wireless heterogeneous networks is based on the coexistence and interoperability of different types of radio access technologies in a unified wireless heterogeneous platform. A key process in the wireless heterogeneous networks is the initiation and execution of vertical handovers. Variety of mechanisms are proposed in the literature that are tailored to optimize the choice of radio...
This paper introduces a novel rendezvous protocol (RAC2E) for dynamic control channel provisioning among cognitive radios in a decentralized and cooperative ad-hoc environments. Unlike previous work in the field, RAC2E does not require synchronization in the radio environment. Its main characteristics are lightweight design and scalability. The paper elaborates RAC2E operation, gives a numerical analysis...
Cognitive Radios have emerged as one the most promising methods to increase wireless system efficiency through dynamic spectrum access combined with other cross-layer optimization methods. Most of the research prototypes and demonstrations have so far focused on either general platforms or scenarios that are predominantly taken from military or emergency communications domain. In this demonstration...
Microeconomics models are widely used for revenue estimation through utility functions and deployed pricing schemes. Utility functions represent the QoS (Quality of Service) perception of the user for a given service while the pricing schemes denote the provider charging policy for a service. This paper proposes novel approach for utility estimation for data traffic in WiMAX and aims to investigate...
Mobility in WSNs can impact the overall network performances. The controlled mobility offers the possibility of relocating sensing resources to areas with more intensive activity and/or decreased sensor density. This paper presents a novel algorithm for sensor nodes relocation that achieves longer sensor network lifetime. The algorithm has distributed approach for sensors mobility, obtaining improved...
A wireless heterogeneous network consists of various wireless networks such as Worldwide Interoperability for Microwave Access (WiMAX), Wireless Fidelity (WiFi), cellular networks etc. Vertical handover (VHO) is a procedure that enables continuous seamless communication in these heterogeneous systems. This paper considers the speed as an aspect of motion as input parameters for the handover decision...
The rapid growth of diverse wireless communication networks, each with its own unique characteristics, led to proliferation of the wireless heterogeneous network concept. The integration of various networks is not trivial, especially if one targets high performances. Modeling and simulation-based analysis provides sufficient means for performance evaluation, even in the abstract phases of the network...
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