Power Control for Cell-Edge User in NOMA Ultra Dense Networks

Abstract

Adjusting user transmission power is an effective approach to managing Inter-Cell Interference (ICI) in Ultra-Dense Networks (UDNs). Thus, users can proactively adjust their transmission power to minimize total power consumption while maintaining the required quality-of-service. Most recent research on power control mechanisms focuses on designing policies that increase the transmission power for all active users, including both near users with good received signal qualities and far users with poor ones. However, since near users-referred to as Cell-Center Users (CCUs)-can already achieve the desired service quality, this paper applies the power control mechanism to far users, known as Cell-Edge Users (CEUs). The uplink coverage probabilities of near and far users are derived under the stretched path loss model and Rayleigh fading for systems with and without the power-domain Non-Orthogonal Multiple Access (NOMA) technique. The analysis shows that the proposed mechanism can significantly reduce transmission power by up to 25% in conventional systems and up to 36.6% in NOMA systems. Moreover, the NOMA system model with the proposed power control mechanism can also improve the ergodic capacity by up to 72.48%.