Abstracts Category : Other

Continuous Ultra-Dense Networks - A System Level Design for Urban Outdoor Deployments

by Petteri Kela

Ultra-dense networks (UDNs) will play a critical role in the future ofmobile communications. Especially within urban street canyons with anextensive amount of mobile users, the propagation environment preventsthe efficient spatial densification by means of macro cell massive MIMOsystems. Hence, increasing the amount of transmission and receptionpoints (TRPs) is the key to success.In this thesis, a system level continuous UDN (C-UDN) concept is developed.In particular, a novel radio frame structure is designed to meetthe low-latency, high-capacity and mobility support requirements of thefuture generation wireless networks. Also the time and frequency domainscheduling framework is further developed in order to support spatial domainscheduling of highly mobile users. Moreover, transmit and receivebeamforming that is based on user location estimates is studied in orderto increase signal-to-interference-plus-noise ratio and decrease pilotoverhead caused by full-band uplink reference signals, commonly usedfor channel state information (CSI) in time-division-duplex TDD systems.Since one of the main challenges for wide-scale deployment of UDNsis the backhaul, also a massive MIMO based sub-6 GHz solution that exploitsspatial multiple-access and TDD for UDN self-backhauling is given.This is shown to outperform self-backhauling that is based on time domainmultiplexing only. What makes this study attractive is that withwireless alternatives to wired solutions, deployment costs can be loweredsignificantly. Furthermore, millimeter wave technologies typically requireline-of-sight conditions, which significantly reduces deployment flexibility.Lastly, an approach for dealing with uplink small packet transmissionsfrom a massive amount of machine type communication (MTC) devices inUDNs is proposed. The proposed approach exploits beamforming baseddistribution of uplink grants for connectionless small data transmissions.Receive beamforming is also employed for receiving subsequent smallpacket transmissions. It is shown that with the proposed approach, lowcollision and decode failure probabilities can be achieved. Additionally,the results provided show that simultaneous reception of such small packettransmissions can be dealt with low latency and low physical resource usageby utilizing spatial receive filters that maximize received power towardsthe directions where grants were broadcasted.; rimmisen tiheill verkoilla tulee olemaan ratkaiseva merkitys tulevaisuudenmatkaviestinnss. Erityisesti kaupunkialueilla radiokanavanetenemisominaisuudet katukuiluissa estvt tehokkaan spatiaalisentihentmisen makro-solujen massiivisilla MIMO -jrjestelmill. Siksi radionoodienhuomattava lisminen on avain menestykseen.Tss vitskirjassa on kehitetty uusi yhtjaksoisen peiton tarjoavatihen verkon jrjestelmtason konsepti. Uusi radion kehysrakenne onsuunniteltu tyttmn uuden sukupolven verkkojen matalan latenssin,suuren kapasiteetin ja kyttjien liikkuvuuden vaatimukset. Mys ajanja taajuuden