Survey of Spectrum Sharing for Inter-Technology Coexistence

Increasing capacity demands in emerging wireless technologies are expected to be met by network densification and spectrum bands open to multiple technologies. These will, in turn, increase the level of interference and also result in more complex inter-technology interactions, which will need to be managed through spectrum sharing mechanisms. Consequently, novel spectrum sharing mechanisms should be designed to allow spectrum access for multiple technologies, while efficiently utilizing the spectrum resources overall. Importantly, it is not trivial to design such efficient mechanisms, not only due to technical aspects, but also due to regulatory and business model constraints. In this survey we address spectrum sharing mechanisms for wireless inter-technology coexistence by means of a technology circle that incorporates in a unified, system-level view the technical and non-technical aspects. We thus systematically explore the spectrum sharing design space consisting of parameters at different layers. Using this framework, we present a literature review on inter-technology coexistence with a focus on wireless technologies with equal spectrum access rights, i.e. (i) primary/primary, (ii) secondary/secondary, and (iii) technologies operating in a spectrum commons. Moreover, we reflect on our literature review to identify possible spectrum sharing design solutions and performance evaluation approaches useful for future coexistence cases. Finally, we discuss spectrum sharing design challenges and suggest future research directions

Risk-Informed Interference Assessment for Shared Spectrum Bands: A Wi-Fi/LTE Coexistence Case Study

Interference evaluation is crucial when deciding whether and how wireless technologies should operate. In this paper we demonstrate the benefit of risk-informed interference assessment to aid spectrum regulators in making decisions, and to readily convey engineering insight. Our contributions are: we apply, for the first time, risk assessment to a problem of inter-technology spectrum sharing, i.e. Wi-Fi/LTE in the 5 GHz unlicensed band, and we demonstrate that this method comprehensively quantifies the interference impact. We perform simulations with our newly publicly-available tool and we consider throughput degradation and fairness metrics to assess the risk for different network densities, numbers of channels, and deployment scenarios. Our results show that no regulatory intervention is needed to ensure harmonious technical Wi-Fi/LTE coexistence: for the typically large number of channels available in the 5 GHz band, the risk for Wi-Fi from LTE is negligible, rendering policy and engineering concerns largely moot. As an engineering insight, Wi-Fi coexists better with itself in dense, but better with LTE, in sparse deployments. Also, both main LTE-in-unlicensed variants coexist well with Wi-Fi in general. For LTE intra-technology inter-operator coexistence, both variants typically coexist well in the 5 GHz band, but for dense deployments, implementing listen-before-talk causes less interference

LTE in Unlicensed Bands is neither Friend nor Foe to Wi-Fi

Proponents of deploying LTE in the 5 GHz band for providing additional cellular network capacity have claimed that LTE would be a better neighbour to Wi-Fi in the unlicensed band, than Wi-Fi is to itself. On the other side of the debate, the Wi-Fi community has objected that LTE would be highly detrimental to Wi-Fi network performance. However, there is a lack of transparent and systematic engineering evidence supporting the contradicting claims of the two camps, which is essential for ascertaining whether regulatory intervention is in fact required to protect the Wi-Fi incumbent from the new LTE entrant. To this end, we present a comprehensive coexistence study of Wi-Fi and LTE-in-unlicensed, surveying a large parameter space of coexistence mechanisms and a range of representative network densities and deployment scenarios. Our results show that, typically, harmonious coexistence between Wi-Fi and LTE is ensured by the large number of 5 GHz channels. For the worst-case scenario of forced co-channel operation, LTE is sometimes a better neighbour to Wi-Fi - when effective node density is low - but sometimes worse - when density is high. We find that distributed interference coordination is only necessary to prevent a "tragedy of the commons" in regimes where interference is very likely. We also show that in practice it does not make a difference to the incumbent what kind of coexistence mechanism is added to LTE-in-unlicensed, as long as one is in place. We therefore conclude that LTE is neither friend nor foe to Wi-Fi in the unlicensed bands in general. We submit that the systematic engineering analysis exemplified by our case study is a best-practice approach for supporting evidence-based rulemaking by the regulator.Comment: accepted for publication in IEEE Acces

Fulfillment Testing Standards in Design of Pre-School Facilities as a Basis for Architectural and Urban Transformation in the Context of Energy Efficiency

This paper analyses examples of existing kindergartens’ buildings in Serbia in terms of meeting the requirements of spatial capacity and compliance with the minimum standards of required area. Surveyed buildings are dating from various periods. Over time, their environments have undergone numerous changes and interventions, so it is important to establish whether basic requirements are been violated. The second parameter is the degree of land availability, and the existence or nonexistence of free space for possible intervention aimed at changing urban context. Finally, the third aspect is the possibility of using the closest environment to amend the urban environment parameters that would affect the local climate change, reducing outside air temperature in summer or increasing in winter, changing direction or stopping unwanted effects of dominant winds. Namely, by the influence on the input parameters, the need for thermal insulation and the method of ventilation could be changed. The norms are dealing predominantly with the external building envelope and with the insulation, which is necessary, but the last in a series of interventions and by far the most expensive, as a solution. Due to frequent climatic anomalies, global trends are going in the direction of prevention, while interventions have been aimed at the urban environment and the use of space resources. Possible changes in city planning, transformation and revitalization of the area would also have a significant impact on the physical environment and the energy efficiency of buildings

HBF MU-MIMO with Interference-Aware Beam Pair Link Allocation for Beyond-5G mm-Wave Networks

Hybrid beamforming (HBF) multi-user multiple-input multiple-output (MU-MIMO) is a key technology for unlocking the directional millimeter-wave (mm-wave) nature for spatial multiplexing beyond current codebook-based 5G-NR networks. In order to suppress co-scheduled users' interference, HBF MU-MIMO is predicated on having sufficient radio frequency chains and accurate channel state information (CSI), which can otherwise lead to performance losses due to imperfect interference cancellation. In this work, we propose IABA, a 5G-NR standard-compliant beam pair link (BPL) allocation scheme for mitigating spatial interference in practical HBF MU-MIMO networks. IABA solves the network sum throughput optimization via either a distributed or a centralized BPL allocation using dedicated CSI reference signals for candidate BPL monitoring. We present a comprehensive study of practical multi-cell mm-wave networks and demonstrate that HBF MU-MIMO without interference-aware BPL allocation experiences strong residual interference which limits the achievable network performance. Our results show that IABA offers significant performance gains over the default interference-agnostic 5G-NR BPL allocation, and even allows HBF MU-MIMO to outperform the fully digital MU-MIMO baseline, by facilitating allocation of secondary BPLs other than the strongest BPL found during initial access. We further demonstrate the scalability of IABA with increased gNB antennas and densification for beyond-5G mm-wave networks.Comment: 13 pages, 11 figures. This work has been submitted to IEEE for possible publication (copyright may be transferred without notice, after which this version may no longer be accessible

Application of Forensic Acoustics and Phonetics in Criminal Proceedings with Special Reference to Examination of Voice Records

Prilikom izbora teme ovog rada autorice su se rukovodile uvjerenjem da se radi o izvanredno aktualnoj i značajnoj temi. Ubrzan i značajan razvoj tehnologije i audio-video tehnike u današnje vrijeme omogućio je zvučno i slikovno snimanje u neusporedivo većem opsegu u odnosu na prošla vremena. Vještačenje u kaznenom postupku jedna je od dokaznih radnji čijim se provođenjem nastoje utvrditi relevantne činjenice za ocjenu postojanja elemenata kaznenog djela ili za ocjenu elemenata o počinitelju i okolnostima počinjenja kaznenog djela. Vještačenja zvučnih i glasovnih zapisa, te vještačenja (poremećaja) glasa, govora i jezika pripadaju specifičnom interdisciplinarnom području nazvanom „forenzička akustika i fonetika“ koje objedinjuje biomedicinske, tehničke i društvene znanosti i koja se povjeravaju iskusnim stručnjacima određenog formalnog obrazovanja zbog prostorno-tehničkih uvjeta, kompleksnosti samog vještačenja i potrebe poštovanja znanstvenih i stručnih akreditiranih metoda kojima se utvrđuju činjenice relevantne za pojedini sudski predmet. Autorice daju pregled ključnih pitanja vezanih uz tehničke snimke činjenica uređene pozitivnim zakonodavstvom uz ukazivanje na mogućnosti primjene vještačenja iz područja forenzičke akustike i fonetike, koje bi značajno pridonijelo učinkovitosti kaznenog postupka. Temeljni je prigovor dosadašnjoj praksi vrlo rijetka primjena vještačenja iz područja forenzičke akustike i fonetike, koja se pretežno odnosi na telekomunikacijska vještačenja, a znatno rjeđe na informatička ili akustička vještačenja, kao i na činjenicu da postoji izuzetno mali broj educiranih vještaka iz ovog područja. Također daju i neke prijedloge de lege ferenda, koji se odnose na širu primjenu u praksi vještačenja forenzičke akustike i fonetike, kao i na stanovite intervencije u zakonski tekst.Expert examination in criminal proceedings is an evidentiary action the conduct of which seeks to establish relevant facts for assessing the existence of elements of a criminal offense or for assessing elements about the perpetrator and the circumstances of the commission of a criminal offense. Expert examining of sound and voice recordings, as well as expert examining of disorders in voice, speech and language belong to a specific interdisciplinary field called “forensic acoustics and phonetics” which unites biomedical, technical and social sciences and which is entrusted to experienced experts of certain formal education due to spatial – technical conditions, the complexity of the expertise itself and the need to respect scientific and professional accredited methods that determine the facts relevant to a particular court case. This paper presents legal and speech language pathology aspects of expert examining, as well as fundamental and applied possibilities of forensic acoustics and phonetics, and special attention is paid to expert examining of voice recordings and voice – speech language pathology in criminal proceedings with listed and analyzed examples from previous cases and harmonization of work and manner of conduct during reconnaissance and evidentiary actions in criminal proceedings. Fundamental criticism of practice to date is of the very rare application of expert examination in forensic acoustics and phonetics which is mainly related to telecommunication examination., and considerably less to cyber or acoustic examination. Criticism is also levelled at the fact that there is an exceptionally small number of educated expert examiners in this area. Also, some solutions de lege ferenda are proffered. These solutions are related to wider application in the practice of expert examination of forensic acoustics and phonetics as well as to certain interventions in law

The Role of Entrepreneurship and Longlife Learning in Branding of Tourism Destination

Brendiranje turističke destinacije ne može se zamisliti bez suradnje privatnog i javnog sektora, poduzetništva i države. Cjeloživotno učenje važan je čimbenik podizanja svijesti tržišta o prednostima turističke destinacije i njezine vrijednosti na tržištu. Definicija brenda koja polazi od potrošača je ona kojom se treba voditi u današnjem tržišnom okruženju u kojem kupac i tržište određuju vrijednost proizvoda ili usluge. Da bi se postiglo uspješno brendiranje destinacije, brend mora postati živ za turiste koji dolaze u destinaciju. Marketinški menadžer moraju biti u mogućnosti ponuditi iskustva i doživljaje kroz posjet destinaciji i pri formiranju brenda, a ne samo razvijati ime, logo i znak. Sve destinacije danas imaju hotele, kongresne kapacitete, jedinstvenu kulturnu baštinu, prirodne ili umjetne atrakcije, zabavne sadržaje ili neke druge oblike turističkih sadržaja kojima nastoje privući pozornost i povećati vrijednost brenda destinacije, ali budući uspjeh ovisi o njihovoj mogućnosti kreiranja jedinstvenog identiteta i diferencijacije u odnosu na konkurenciju. Da bi se destinacija uspješno brendirala potrebno je sudjelovanje svih nositelja turističke ponude zajedno s krovnim nacionalnim institucijama te njihov koordinirani rad na razvoju destinacije, njenoj promidžbi, pružanju jedinstvene i konzistentne kvalitete usluge. Uključivanje poduzetništva i cjeloživotnog učenja o specifičnostima brendiranja turističke destinacije predstavljaju osnovne preduvjete za njeno uspješno brendiranje.Branding of tourism destination can’t be seen without cooperation between private and public sector, entrepreneurship and government. Lifelong learning is an important element of increased awareness about the market and advantages of tourism destination as well as its market value. Definition of brand which starts from the needs of consumers is one that should lead in contemporary market environment where customers and market determine the value of the product or services. To achieve successful branding of destination brand must become alive for tourists visiting destination. Marketing management must be able to create experiences for tourists while visiting destination through creation of brand instead of creating only the name or sign. All destinations today consist of hotels, congress halls, unique cultural, natural or manmade attractions, entertainment, amusement and other facilities in order to attract attention and increase the value of destination brand, but future success depends on their capability of creating unique identity and differentiation from competitors. In order to successfully manage branding of destination, cooperation of all carriers of tourism supply is necessary, together with national institutions and their coordinated work on the destination development, promotion and offering unique and consistent quality of service. Involvement of entrepreneurship and lifelong learning about specific issues related to branding of tourism destination are basic prerequisites of its successful branding

Совершенствование транспортных комплексов гранитных карьеров

Проведен анализ основных технологических схем транспортирования горной массы в условиях гранитных карьеров Украины. Предложены новые технологические схемы карьерного транспорта с использованием канатных напочвенных дорог.Проведен анализ основных технологических схем транспортирования горной массы в условиях гранитных карьеров Украины. Предложены новые технологические схемы карьерного транспорта с использованием канатных напочвенных дорог