NOMA Integrated with Enabling Technologies and Practical Challenges

Non-orthogonal multiple access (NOMA) schemes allow multiple users to share the same resource and separate the users in either the power-domain (PD -NOMA) or in the code domain (CD-NOMA). To make NOMA a reality in networks, several important practical challenges need to be considered. This thesis addresses some of these challenges in both the PD-NOMA and CD-NOMA space. In PD-NOMA systems integrated with mmWave technology, the thesis considers the practical constraint of the end user processing capabilities, modelled through an SIC decoding capability constraint that captures the number of other user’s signals any given user can decode in the SIC decoding procedure. 6G networks are expected to include a mix of users of varying processing capabilities, all needing to access the same spectrum. To solve the rate maximization problem when each user has different processing capabilities, the thesis proposes low-complexity heuristics to maximize the sum-rate after factoring in each individual users SIC decoding capability constraint. However, these algorithms are based on the instantaneous channel conditions of users and need to be run on a millisecond granularity. To address this, a machine learning based neural network approach is proposed that takes this complexity offline where the neural network is trained on simulated and past network data, and the trained network is directly applied to solve the clustering problem in live networks. The thesis also addresses the practical constraint around the availability of CSI by exploiting the growing field of integrated communication and sensing solutions using a camera equipped base station to aid the user clustering process in NOMA. In CD-NOMA systems using the widely promoted sparse code multiple access (SCMA) scheme for uplink (UL) NOMA, the thesis studies the PAPR problem in UL SCMA-OFDM systems. A novel link between the obtained PAPR statistics and the SCMA modulation scheme and the placement of the sub-carriers (SC’s) that carry the SCMA codewords is presented. The thesis highlights unique opportunities that SCMA-OFDM systems present to the widely studied PAPR problem due to the statistical dependency between the OFDM SCs carrying the codewords as opposed to traditional OFDM systems where the SCs are independently modulated.

Name thesis:degree_name

Doctor of Philosophy (Ph.D.)

Level thesis:degree_level

Doctoral

Discipline thesis:degree_discipline

Engineering, Electrical and Computer

Grantor dc:publisher

Carleton University

Year dc:date.issued

2023

Author dc:creator

• Rajasekaran, Aditya

Statement dc:rights

• Copyright © 2023 the author(s). Theses may be used for non-commercial research, educational, or related academic purposes only. Such uses include personal study, distribution to students, research and scholarship. Theses may only be shared by linking to the Carleton University Institutional Repository and no part may be copied without proper attribution to the author; no part may be used for commercial purposes directly or indirectly via a for-profit platform; no adaptation or derivative works are permitted without consent from the copyright owner.

Language dc:language.iso

en

DOI

10.22215/etd/2023-15832

OAI identifier oai:identifier

oai:carleton.scholaris.ca:20.500.14718/41759