Multiplexing services in 5G new radio: optimal resource allocation based on mixed numerology and mini-slot approach

Abstract

In order to meet the diverse requirements imposed by a massive number of applications, the fifth generation (5G) New Radio (NR) Physical Layer (PHY) is designed to provide a highly flexible framework. This flexibility is made possible through a scalable numerology. The term numerology refers to the PHY waveform parametrization and allows the use of different subcarrier spacings, symbol and slot durations. In addition to an efficient support of various service requirements, employing a scalable numerology allows a better adjustment of the PHY waveform to different channel conditions, providing more robustness against channel variations. Despite increased flexibility provided by multiplexing different numerologies, there is also a drawback of this concept, i.e., Internumerology Interference (INI) caused by non-orthogonal subcarriers between different numerologies. In this thesis, a closed-form expression of INI is derived for both, Cyclic Prefix (CP)-Orthogonal Frequency Division Multiplexing (OFDM) and Universal Filtered Multicarrier (UFMC) as a possible beyond 5G technology. In addition to INI, interference induced by doubly-selective channels as well as the channel estimation error are considered in this thesis. Considering a multi-user mixed numerology scenario under different channel conditions, a novel optimization algorithm for joint numerology and resource allocation is proposed in the thesis. The proposed algorithm is first represented by the optimal Integer Linear Programming (ILP) solution. In order to reduce the computational complexity for large scale scenarios with many users and/or large transmission bandwidth, several less complex methods are proposed. The tradeoff between the performance and complexity is also discussed. To multiplex different applications within the same band and thereby enhance the adaptability of the PHY, Third Generation Partnership Project (3GPP) proposes the mini-slot concept in addition to the mixed numerology concept. Employing these two concepts, this thesis proposes novel optimization algorithms for the joint numerology and resource allocation considering both, different channel conditions and user requirements. Emphasis is, in particular, placed on the achievement of Low Latency (LL) communications. Furthermore, the impact of UFMC on the performance is also discussed.