Network Coding-Assisted Retransmission Scheme for Video- Streaming Services over Wireless Access Networks

Video-streaming services, such as Internet protocol television, promising the delivery of multimedia contents over wireless access networks to clients whenever and wherever, are becoming more and more popular. However, scarce radio resources, lossy characteristics of wireless links and high bandwidth demands pose the never-ending challenges for provisioning of real-time streaming services over wireless networks in a timely and reliable manner. Furthermore, a wireless channel may suffer from interference and multipath fading, which may cause random packet losses. In addition, wireless link layer does not provide a retransmission mechanism for multicast/broadcast traffic. This would significantly impact the clients’ quality of experience of streaming services. Traditional unicast retransmission solutions improve client’s quality, at the bandwidth expense, because every lost packet must be retransmitted separately. This chapter presents and practically evaluates a retransmission scheme for video-streaming services over last mile wireless networks. It is based on network coding techniques that increase the overall performance by means of reducing the number of physical transmissions, in comparison to traditional unicast retransmission approach, resulting in reduced bandwidth consumption. Thus, the Internet service providers can increase the number of clients over the same infrastructure or, alternatively, offer more services to the clients

SDL-Based Automatic Test Generation for GSM Services

The paper introduces automatic test scenario generation for GSM (Global System for Mobile communications) services. The first step of the test scenario generation, which cannot be fully automated, is to create an SDL (Specification and Description Language) description of a GSM service. We propose a methodology for transforming an informal service description to an SDL specification. The form and contents of the resulting specification are adapted to the properties of the test derivation method. The next three steps of the test scenario generation are abstraction of an EFSM (Extended Finite State Machine) to a FSM (Finite State Machine), generation of test sequences and translation to TTCN (Tree and Tabular Combined Notation). These steps are completely automated in the tool iATS. The process of the automatic test scenario generation is illustrated by the example of test scenario generation for the GSM call setup

User-Centric Proximity Estimation Using Smartphone Radio Fingerprinting

The integration of infectious disease modeling with the data collection process is crucial to reach its maximum potential, and remains a significant research challenge. Ensuring a solid empirical foundation for models used to fill gaps in data and knowledge is of paramount importance. Personal wireless devices, such as smartphones, smartwatches and wireless bracelets, can serve as a means of bridging the gap between empirical data and the mathematical modeling of human contacts and networking. In this paper, we develop, implement, and evaluate concepts and architectures for advanced user-centric proximity estimation based on smartphone radio environment monitoring. We investigate innovative methods for the estimation of proximity, based on a person-radio-environment trace recorded by the smartphone, and define the proximity parameter. For this purpose, we developed a smartphone application and back-end services. The results show that, with the proposed procedure, we can estimate the proximity of two devices in terms of near, medium, and far distance with reasonable accuracy in real-world case scenarios

User-Centric Proximity Estimation Using Smartphone Radio Fingerprinting

The integration of infectious disease modeling with the data collection process is crucial to reach its maximum potential, and remains a significant research challenge. Ensuring a solid empirical foundation for models used to fill gaps in data and knowledge is of paramount importance. Personal wireless devices, such as smartphones, smartwatches and wireless bracelets, can serve as a means of bridging the gap between empirical data and the mathematical modeling of human contacts and networking. In this paper, we develop, implement, and evaluate concepts and architectures for advanced user-centric proximity estimation based on smartphone radio environment monitoring. We investigate innovative methods for the estimation of proximity, based on a person-radio-environment trace recorded by the smartphone, and define the proximity parameter. For this purpose, we developed a smartphone application and back-end services. The results show that, with the proposed procedure, we can estimate the proximity of two devices in terms of near, medium, and far distance with reasonable accuracy in real-world case scenarios

Integrated Communications and Sensing in Terahertz Band: A Propagation Channel Perspective

The rise of new requirements for future wireless systems is leading to a convergence of communication systems toward very high carrier frequencies, wide bandwidth, and massive antenna arrays. Understanding the properties of terahertz (THz) electromagnetic waves is critical for integrated communication and sensing (ISAC) system development and optimization. Therefore, in this paper, we investigate the propagation channel parameters and the applicability of terahertz electromagnetic waves for integrated communications and sensing. In doing so, we explore the new challenges and differences that arise when moving from systems operating at frequencies below the terahertz frequency bands

Framework for the Machine Learning Based Wireless Sensing of the Electromagnetic Properties of Indoor Materials

Available digital maps of indoor environments are limited to a description of the geometrical environment, despite there being an urgent need for more accurate information, particularly data about the electromagnetic (EM) properties of the materials used for walls. Such data would enable new possibilities in the design and optimization of wireless networks and the development of new radio services. In this paper, we introduce, formalize, and evaluate a framework for machine learning (ML) based wireless sensing of indoor surface materials in the form of EM properties. We apply the radio-environment (RE) signatures of the wireless link, which inherently contains environmental information due to the interaction of the radio waves with the environment. We specify the content of the RE signature suitable for surface-material classification as a set of multipath components given by the received power, delay, phase shift, and angle of arrival. The proposed framework applies an ML approach to construct a classification model using RE signatures labeled with the environmental information. The ML method exploits the data obtained from measurements or simulations. The performance of the framework in different scenarios is evaluated based on standard ML performance metrics, such as classification accuracy and F-score. The results of the elementary case prove that the proposed approach can be applied for the classification of the surface material for a plain environment, and can be further extended for the classification of wall materials in more complex indoor environments

Does building identity still exist?

V članku je predstavljena vsebina o redefiniciji kontinuitete in prepoznavnosti elementov stavbne identitete pri novejših gradnjah, v kontekstu arhitekturnih regij in krajin, ki jih je v 90-ih letih prejšnjega stoletja določil prof. Peter Fister. Zaradi množičnosti »samograditeljskih« posegov v 80-ih se je kontinuiteta prenosa tradicionalnih elementov stavbne dediščine na novogradnje prekinila – tako na nivoju posamezne stavbe kot tudi na nivoju naselja. V članku je opisan postopek odkrivanja in, s pomočjo sodobnih programskih orodij, vrednotenja tistih primerov novejših gradenj, pri katerih je bilo, kljub vplivom različnih trendov, mogoče prepoznati ohranitev tradicionalnih nosilcev stavbne identitete. Raziskava na nivoju naselja in stavbe je bila opravljena na območju Prebolda v Savinjsko-kozjanski arhitekturni regiji, v študiji posameznih stavb pa so bili vključeni primeri dobre prakse iz celotnega območja Slovenije. Hkrati so bili vsebinsko nadgrajeni Fistrovi »popisni kartoni«, ki sedaj bolj sistematično opredeljujejo lego stavbe znotraj naselja, ter njene volumetrične in ploskovne likovne elemente, ki so nosilci identitete.The article presents the redefinition of the continuity and visibility of the elements of building identity in recent buildings, in the context of the architectural regions and landscapes defined by Prof. Peter Fister in the 1990s. The mass of »self-build« interventions in the 1980s led to a break in the continuity of the transfer of traditional elements of the built heritage to new buildings - both at the level of the individual building and at the level of the settlement. The article describes the process of discovering and, with the help of modern software tools, evaluating those examples of recent construction where, despite the influence of various trends, it was possible to identify the preservation of traditional building identity elements. The research at the settlement and single building level was carried out in the area of Prebold in the Savinjsko-kozjanska architectural region, while the study of individual buildings included examples of good practice from the whole territory of Slovenia. At the same time, Fister’s »inventory cards« were upgraded in terms of content, which now more systematically define the position of the building within the settlement and its volumetric and planar visual elements, which are the carriers of identity

Outdoor fingerprint localization with BLE beacons

Introduction The data set contains received signal strength (RSS) measurements made with Bluetooth Low Energy (BLE) technology, which can be used for outdoor fingerprint-based localization applications, as presented in an article "LOG-a-TEC Testbed Outdoor Localization Usign BLE Beacons". Measurement setup The measurements were created with WL1837MOD radio connected to a in-house embedded device. The data set was collected with 40 nodes of the LOG-a-TEC testbed positioned at the campus of the Jožef Stefan Institute, Ljubljana. The experimentation area is composed of 5 x 26 positions separated by 1.2 m covering 150 square meters. On each position a mobile phone was broadcasting BLE advertising beacons with power of -2 dBm in interval of 100 ms. Surrounding testbed nodes were collecting the beacons for approximately a minute for each position. Data set Measurements are stored in JSON format where each object contains rss measurement (in dBm) with corresponding timestamp (in seconds). The folder contains two JSON files: spring_data.json - measurements made in May 2022, winter_data.json - smaller measurements made in December 2021. This data set contains only the measurements from the middle row of the campus park.This research was funded by Slovenian Research Agency (ARRS) grant numbers P2-0016, P2-0016 - "COVID extension" and J2-4461