Analysis of Power Allocation for Non-Orthogonal Multiple Access

Abstract

Most multiple access schemes provide orthogonal access to the users in time, frequency, code and space, this is not true for NOMA, where each user operates in the same band and at the same time where they are distinguished by their power levels. It uses superposition coding at the transmitter such that the successive interference cancellation (SIC) receiver can separate the users both in the uplink and in the downlink channels. The users in (NOMA) are classified based on power, while in Orthogonal Multiple Access (OMA) it is classified based on time, frequency, and code. The NOMA system contains a power-delay tradeoff and hence power efficiency becomes critical for Ultra-Reliable Low Latency Communication (URLLC), especially where a huge number of devices are battery-powered. Combining these considerations, we simulate Dynamic Power Allocation (DPA) for power domain non-orthogonal multiple access (PD-NOMA) with user mobility. For small and clumsy battery-powered IoT devices, power efficiency becomes critical. Further, flexibility is also important to communicate with diverse machine-type devices as well as human users while meeting a variety of quality of service (QoS) requirements. The performance of the DPA is compared with Static Power Allocation under user mobility.

Zipf Distribution Power AllocationAapproach for NOMA Systems

“…This section illustrates the performance of a NOMA downlink system with three different power allocation methods using the same simulation parameters. The simulation compares the performance of Zipf PA with Pair PA cited in [47]- [49] and Generalized PA that emerged in [50], [17]. The results are presented in terms of achievable capacity, SNR, spectral efficiency SE and energy efficiency EE, with a large number of users network model.…”