UNIVERSIT`
A DI PISA
DIPARTIMENTO DI INGEGNERIA DELL’INFORMAZIONE
Dottorato di Ricerca in Ingegneria dell’Informazione
Abstract of the Dissertation by the Student Carmine VITIELLO - XXIX
cycle of the PhD Program
Tutor(s): Prof. Marco Luise
1. Abstract
This thesis focuses on the development of the Universal Filtered Multicarrier(UFMC) waveform, proposed as a candidate to 5G physical layer. Unlike OFDM, this waveform groups a certain number of subcarriers into a subband, performing a signal processing and applying a filtering operation on that. In this way, UFMC provides a further degree of freedom in terms of flexibility, improving the robustness against frequency and time misalignments, reducing the Out-of-Band (OOB) emissions and increasing the spectral efficiency. In the first part of the thesis, an overview of the physical layer 5G requirements, highlighting the limits of the previous generation. Then, OFDM and the main proposed waveforms as 5G candidates are characterized, discussing about strong and weak aspects of each one. Furthermore, an analytical description of UFMC followed by a brief comparison in terms of time and frequency efficiency is given. Given that no resource allocation technique has been found in literature, different strategies are proposed for further improving the UFMC performance, maximizing a figure of merit called goodput. This strategies exploits a Bit Interleave Coded (BIC) modulation applied to UFMC and they are qble to select the best transmission parameters, namely code rate, modulation, power and number of transmitted multicarrier symbols, using an iterative greedy algorithm and exploiting the granularity of the waveform. The techniques performance are evaluated using different channel models, assuming both perfect and imperfect synchronization, and supposing different transmitting data size in order to evaluate the resource allocation and UFMC behaviour for continuous or sporadic communications, the latter typical of the Internet of Things (IoT). Moreover, the UFMC waveform has been implemented thanks by an open-source development framework called OpenAirInterface. After an accurate theoretical analysis of the transceiver chain, UFMC transmitter has been simplified, paying attention to preserve the benefits and the features of the waveform and improving the performance in terms of computational complexity. The implementation is performed over the PUSCH LTE channel, just substituting SC-FDMA modulator with the reduced-complexity UFMC one, while, at the receiver side, a timing synchronization block has been included for enabling the standard PUSCH receiver to receive UFMC signal correctly. The performance in terms of computational complexity and block error rate proved and confirmed the qualities of the UFMC on the typical application scenarios, especially when coarse synchronization is assumed. The implementation process within the 3GPP LTE stack and the relative simulations have even demonstrated the coexistence of the UFMC waveform with the current physical layer, satisfying an important requirement for the gradual transition from the forth to the fifth mobile generation. Pisa , 09/01/2017
The student The Tutor
Carmine VITIELLO Prof. Marco Luise
