An ultra-wideband sensing board for IoT

In this paper, we present an ultra-wideband impedance sensing board for the radio-frequency front-ends used in wireless units for the Internet of Things and the fifth-generation wireless communication systems. We adopt as an impedance sensing board a six-port junction which was designed, fabricated, and tested experimentally in the frequency range from 5 GHz to 6 GHz. Moreover, the sensing board functionality was fully validated with load-pull measurements carried out in the same frequency range

Модель оцінки мобільності інформаційно-телекомунікаційної мережі спеціального призначення

Завдання забезпечення зв’язку між органами управління в системі управління військами Збройних Сил України є актуальним завданням під час проведення антитерористичної операції. З метою підвищення ефективності управління підрозділами виникає гостра необхідність в використанні оцінки найбільш істотних показників ефективності функціонування інформаційно-телекомунікаційної мережі спеціального призначення. Результати дослідження існуючих моделей та методик оцінки мобільності розкривають їх обмежені можливості і визначають необхідність використання моделі, більш зручної для оцінки мобільності даної мережі. В статті розглядається модель оцінки мобільності інформаційно-телекомунікаційної мережі спеціального призначення, яка може бути використана для визначення рівня ймовірності вчасного виконання заходів щодо зміни її структури. Фактори і параметри процесу експлуатації інформаційнотелекомунікаційної мережі спеціального призначення відбивають динаміку функціонування даної системи. Оцінка значень удосконалених показників може дозволити виконувати порівняння і вибір оптимальної стратегії діяльності системи в складних умовах. В подальшому розрахунок значень отриманих показників може забезпечити прогноз результатів функціонування інформаційно-телекомунікаційної мережі спеціального призначення шляхом спрямованого поліпшення якості прийнятого рішення

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

Evolution Toward 5G Mobile Networks - A Survey on Enabling Technologies

In this paper, an extensive review has been carried out on the trends of existing as well as proposed potential enabling technologies that are expected to shape the fifth generation (5G) mobile wireless networks. Based on the classification of the trends, we develop a 5G network architectural evolution framework that comprises three evolutionary directions, namely, (1) radio access network node and performance enabler, (2) network control programming platform, and (3) backhaul network platform and synchronization. In (1), we discuss node classification including low power nodes in emerging machine-type communications, and network capacity enablers, e.g., millimeter wave communications and massive multiple-input multiple-output. In (2), both logically distributed cell/device-centric platforms, and logically centralized conventional/wireless software defined networking control programming approaches are discussed. In (3), backhaul networks and network synchronization are discussed. A comparative analysis for each direction as well as future evolutionary directions and challenges toward 5G networks are discussed. This survey will be helpful for further research exploitations and network operators for a smooth evolution of their existing networks toward 5G networks

Channel Simulators for MmWave and 5G Applications

Along with the tremendous growth of extremely high traffic demand, 5G radio access technology, is becoming the core component to support massive and multifarious connected devices and real-time, and to offer high reliability wireless communications with high data rate. And millimeter-wave (mmWave) range with a huge frequency spectrum from 3 GHz to 300GHz will perfectly meet the multi-gigabit communicative demand. However, mmWave usage also generally brings new challenges, such as coping with high attenuation or path losses. As an effective method to evaluate the performance of the new concept in communication networks, nowadays, several channel models and simulators have been proposed and developped, such as, WINNER, COST-2100, IMT-Advanced, METIS, NYU Wire-less and QuaDRiGa etc. The thesis goals have been to offer an overview of the advantages and disadvantages of various mmWave channel models existing in the literature, based on the published literature, and to compare based on simulations some of the main features of two selected open-source models, namely the WINNER 2 and QuaDRiGa channel models. In the future, more mmWave channel models are planned to be tested and simulated for a better understanding of their suitability for various mmWave applications

Nonlinear impairments and mitigation technologies for the next generation fiber-wireless mobile fronthaul networks

The proliferation of Internet-connected mobile devices and video-intensive services are driving the growth of mobile data traffic in an explosive way. The last mile of access networks, mobile fronthaul (MFH) networks, have become the data rate bottleneck of user experience. The objective of this research are two-fold. For analog MFH, nonlinear interferences among multiple bands of mobile signals in a multi-RAT multi-service radio-over-fiber (RoF)-based MFH system are investigated for the first time. The nonlinear impairments of both single-carrier and multi-carrier signals are investigated, and it is experimentally demonstrated that inter-channel interferences play a more important role in the performance degradation of analog MFH than the nonlinear distortions of each individual signal. A digital predistortion technique was also presented to linearize the analog MFH links. On the other hand, for digital MFH, we experimentally demonstrate a novel digitization interface based on delta-sigma modulation to replace the state-of-the-art common public radio interface (CPRI). Compared with CPRI, it provides improved spectral efficiency and enhanced fronthaul capacity, and can accommodate both 4G-LTE and 5G mobile services.Ph.D