Design and analysis of non-orthogonal multiple access in communication systems

Abstract

Non-Orthogonal Multiple Access (NOMA) has emerged as a promising technique to satisfy the high demand of users in future wireless networks. The NOMA literature is heavily based on Power-Domain NOMA (PD-NOMA), which inherently needs a power imbalance between superposed user signals. Another technique is based on using two sets of signal waveforms and is referred to as Waveform Domain NOMA (WD-NOMA). One of the forms of WD-NOMA is NOMA-2000 which does not need any power imbalance and avoids the outage floors typically encountered in PD-NOMA. In this thesis, we provide theoretical analyses of both PD-NOMA and NOMA-2000 using the performance metrics such as the outage probability and channel capacity. In NOMA literature on capacity calculations generally perfect successive interference cancelation (SIC) is assumed, which is not realistic due to the error floors in biterror and outage performances. Therefore, we consider capacity under the imperfect SIC approach which basically is based on the assumption that if a user is in outage, its signal cannot be cancelled perfectly with SIC. The analysis is rst presented for Rayleigh fading channels and then enhanced to generalized fading channels described by the ?-? fading model. Our analysis not only shows that compared to PD-NOMA and Orthogonal Multiple Access (OMA), NOMA-2000 has superior performance but also indicates that NOMA-2000 can reach analytical lower/upper bounds in most cases. Overall, our analysis and results con rm that NOMA-2000 represents a very attractive multiple access technique for future wireless networks.