Doctoral dissertation

Alternative low-complexity waveforms for fifth generation mobile network and beyond

The forthcoming fifth generation (5G) mobile network aims at versatile and reliable services used in different aspects of our daily life. The candidate waveforms seem to have two possible directions: simple and wasting resources (especially spectrum-wise), or highly complex and conserving resources. M.Sc. AlaaEddin Loulou in his doctoral research has investigated the complexity issues of the 5G candidate waveforms and proposed computationally efficient implementations of these waveforms.

The new fifth generation (5G) mobile communication networks promise enormous and diverse services to mobile users. In fact, 5G is not only for the human users but it will also connect machines, devices, and sensors. This non-human connection is called internet of things (IoT).

The wider application domain is not the only challenging aspect with the future networks, but the waveform design requirements have been aggravated as well. The currently used waveform, cyclic prefix – orthogonal frequency division multiplexing (CP-OFDM), has certain non-idealities which are pronounced when developing the next generation multi-service wireless network. Especially, these non-idealities limit the effective use of radio spectrum while transmission schemes are adapted to different service requirements. Various other waveform candidates achieve, generally, better use of the frequencies. Nevertheless, those candidates require intensive computational complexity.

Loulou formulates his research question as follows: “Can we achieve sufficient reduction in computational complexity through the two investigated approaches to make them interesting for practical devices? The quantitative target is to reach the complexity of plain CP-OFDM for filtered OFDM in general narrowband scenarios, and to reach significantly lower complexity in the specific case study on narrowband IoT.”

To answer that, the thesis has investigated various waveforms and related signal processing techniques proposed in the literature while focusing on their spectral containments and computational complexity. The thesis gives a special attention to the waveforms based on fast-convolution processing and narrowband scenarios. Especially in the case of narrowband IoT devices, the signal processing solutions proposed in the thesis require considerably lower complexity when compared with existing techniques. Moreover, the thesis demonstrates that the waveform of simple low-rate devices can be implemented without the need of general multiplications, which helps to reduce the cost and power consumption.

AlaaEddin Loulou hails from Palestine, has lived in Tampere for eight years. Currently, he works with Nokia mobile networks as system-on-chip engineer.

The doctoral dissertation of M.Sc. AlaaEddin Loulou in the field of computing and electrical engineering entitled Low-Complexity Multicarrier Waveform Processing Schemes for Future Wireless Communications will be publicly examined in the Faculty of Information Technology and Communication Sciences at Tampere University at 12 o’clock on Friday 22.11.2019 in the auditorium TB109 of Tietotalo, Korkeakoulunkatu 1, Tampere. The Opponent will be Professor Håkan Johansson from Linköping University, Sweden. The Custos will be Professor Markku Renfors from the Faculty of Information Technology and Communication Sciences.

The dissertation is available online at the http://urn.fi/URN:ISBN:978-952-03-1349-4