Efficient joint channel equalization and tracking for V2X communications using SC-FDE schemes

Our aim with this paper is to present a solution suitable for vehicle-to-everything (V2X) communications, particularly, when employing single-carrier modulations combined with frequency-domain equalization (SC-FDE). In fact, we consider the V2X channel to be doubly-selective, where the variation of the channel in time is due to the presence of a Doppler term. Accordingly, the equalization procedure is dealt by a low-complexity iterative frequency-domain equalizer based on the iterative block decisionfeedback equalization (IB-DFE) while the tracking procedure is conducted employing an extended Kalman filter (EKF). The proposed system is very efficient since it allows a very low density of training symbols, even for fast-varying channels. Furthermore only two training symbols are required to initialize the tracking procedure. Thus, ensuring low latency together with reduced channel estimation overheads.publishe

Single- versus Multi-Carrier Terahertz-Band Communications: A Comparative Study

The prospects of utilizing single-carrier (SC) and multi-carrier (MC) waveforms in future terahertz (THz)-band communication systems remain unresolved. On the one hand, the limited multi-path components at high frequencies result in frequency-flat channels that favor low-complexity wideband SC systems. On the other hand, frequency-dependent molecular absorption and transceiver characteristics and the existence of multi-path components in indoor sub-THz systems can still result in frequency-selective channels, favoring off-the-shelf MC schemes such as orthogonal frequency-division multiplexing (OFDM). Variations of SC/MC designs result in different THz spectrum utilization, but spectral efficiency is not the primary concern with substantial available bandwidths; baseband complexity, power efficiency, and hardware impairment constraints are predominant. This paper presents a comprehensive study of SC/MC modulations for THz communications, utilizing an accurate wideband THz channel model and highlighting the various performance and complexity trade-offs of the candidate schemes. Simulations demonstrate that discrete-Fourier-transform spread orthogonal time-frequency space (DFT-s-OTFS) achieves a lower peak-to-average power ratio (PAPR) than OFDM and OTFS and enhances immunity to THz impairments and Doppler spreads, but at an increased complexity cost. Moreover, DFT-s-OFDM is a promising candidate that increases robustness to THz impairments and phase noise (PHN) at a low PAPR and overall complexity.Comment: 18 pages, 12 figures, journa

Millimetriaaltopohjainen runkoyhteys ultratiheille langattomille verkoille - Itseasentuvien verkkoelementtien analyysi

The amount of wireless traffic and number of connected devices are expected to explode in the coming future. By the year 2020 the amount of data traffic is forecasted to grow 1000 times from 2010 levels and the amount of connected devices is expected to reach 50 billion. One reason to these numbers is massive increase in machine type communications. 5G networks have been envisioned to address these challenges. In the 5G network concept the networks are getting denser than ever before. Millimeter wave communications play an important role in backhauling of the mobile traffic as deploying optical fiber to every small node is most likely going to be too cost intensive for operators. Efficient deployment of an ultra-dense wireless network requires that the devices support so called “plug and play” installation. In practice it means that a mechanic installing a new radio node should only perform physical mounting of the device. Antenna alignment and link setup processes should be fully automated. The purpose of this thesis is to study practical issues and possible solutions of realizing the plug and play installation in a cost efficient way. This study will define scenarios and functional requirements of adding access nodes to backhaul networks. Technical evaluation of link discovery process and cost analysis on plug and play installation of access nodes are conducted.Tulevaisuudessa langattomien laitteiden määrän ja niiden generoiman liikenteen odotetaan kasvavan räjähdysmäisesti. Vuoteen 2020 mennessä verkoissa siirrettävien datamäärien on ennustettu kasvavan tuhatkertaisiksi vuoden 2010 tasosta, ja liitettyjen laitteiden määrän odotetaan nousevan 50 miljardiin. Yksi syy näihin on koneiden välisen viestinnän massiivinen kasvu. 5G-verkkoja on kaavailtu vastaamaan edellä mainittuihin haasteisiin. Osana 5G-konseptia verkkojen odotetaan rakentuvan tiheämmiksi kuin koskaan aiemmin. Millimetriaaltoihin pohjautuvat linkit tulevat olemaan merkittävässä roolissa mobiilidatan siirtämisessä radionoodeista runkoverkkoon, koska optisen kuidun rakentaminen jokaiselle pienelle noodille tulisi mitä luultavimmin operaattoreille liian kalliiksi. Ultratiheiden verkkojen tehokas rakentaminen vaatii, että asennettavat laitteet tukevan niin sanottua itseasennusta. Käytännössä se tarkoittaa sitä, että asentajan täytyy ainoastaan suorittaa radionoodin fyysinen asennus. Antenniensuuntaus- ja linkinmuodostusprosessien tulisi olla täysin automatisoituja. Tämän diplomityön tarkoituksena on tutkia kustannustehokkaaseen itseasennukseen liittyviä käytännön ongelmia sekä mahdollisia ratkaisuita. Tutkimus määrittelee skenaariot ja funktionaaliset vaatimukset radionoodien lisäämiseksi osaksi operaattorin verkkoa. Työ sisältää linkkienmuodostusprosessin teknisen evaluoinnin, sekä kustannusanalyysin tiheiden verkkojen rakentamisesta hyödyntäen itseasennustekniikkaa

Millimetre wave frequency band as a candidate spectrum for 5G network architecture : a survey

In order to meet the huge growth in global mobile data traffic in 2020 and beyond, the development of the 5th Generation (5G) system is required as the current 4G system is expected to fall short of the provision needed for such growth. 5G is anticipated to use a higher carrier frequency in the millimetre wave (mm-wave) band, within the 20 to 90 GHz, due to the availability of a vast amount of unexploited bandwidth. It is a revolutionary step to use these bands because of their different propagation characteristics, severe atmospheric attenuation, and hardware constraints. In this paper, we carry out a survey of 5G research contributions and proposed design architectures based on mm-wave communications. We present and discuss the use of mm-wave as indoor and outdoor mobile access, as a wireless backhaul solution, and as a key enabler for higher order sectorisation. Wireless standards such as IEE802.11ad, which are operating in mm-wave band have been presented. These standards have been designed for short range, ultra high data throughput systems in the 60 GHz band. Furthermore, this survey provides new insights regarding relevant and open issues in adopting mm-wave for 5G networks. This includes increased handoff rate and interference in Ultra-Dense Network (UDN), waveform consideration with higher spectral efficiency, and supporting spatial multiplexing in mm-wave line of sight. This survey also introduces a distributed base station architecture in mm-wave as an approach to address increased handoff rate in UDN, and to provide an alternative way for network densification in a time and cost effective manner

Cooperative Radio Communications for Green Smart Environments

The demand for mobile connectivity is continuously increasing, and by 2020 Mobile and Wireless Communications will serve not only very dense populations of mobile phones and nomadic computers, but also the expected multiplicity of devices and sensors located in machines, vehicles, health systems and city infrastructures. Future Mobile Networks are then faced with many new scenarios and use cases, which will load the networks with different data traffic patterns, in new or shared spectrum bands, creating new specific requirements. This book addresses both the techniques to model, analyse and optimise the radio links and transmission systems in such scenarios, together with the most advanced radio access, resource management and mobile networking technologies. This text summarises the work performed by more than 500 researchers from more than 120 institutions in Europe, America and Asia, from both academia and industries, within the framework of the COST IC1004 Action on "Cooperative Radio Communications for Green and Smart Environments". The book will have appeal to graduates and researchers in the Radio Communications area, and also to engineers working in the Wireless industry. Topics discussed in this book include: • Radio waves propagation phenomena in diverse urban, indoor, vehicular and body environments• Measurements, characterization, and modelling of radio channels beyond 4G networks• Key issues in Vehicle (V2X) communication• Wireless Body Area Networks, including specific Radio Channel Models for WBANs• Energy efficiency and resource management enhancements in Radio Access Networks• Definitions and models for the virtualised and cloud RAN architectures• Advances on feasible indoor localization and tracking techniques• Recent findings and innovations in antenna systems for communications• Physical Layer Network Coding for next generation wireless systems• Methods and techniques for MIMO Over the Air (OTA) testin

Single-Frequency Network Terrestrial Broadcasting with 5GNR Numerology

L'abstract è presente nell'allegato / the abstract is in the attachmen