Enhanced Fairness and Scalability of Power Control Schemes in Multi-Cell Massive MIMO

Abstract

This paper studies the transmit power optimization in multi-cell massive multiple-input multiple-output (MIMO) systems. Network-wide max-min fairness (NW-MMF) and networkwide proportional fairness (NW-PF) are two well-known power control schemes in the literature. The NW-MMF focus on maximizing the fairness among users at the cost of penalizing users with good channel conditions. On the other hand, the NW-PF focuses on maximizing the sum SE, thereby ignoring fairness, but gives some extra attention to the weakest users. However, both of these schemes suffer from a scalability issue which means that for large networks, it is highly probable that one user has a very poor channel condition, pushing the spectral efficiency (SE) of all users towards zero. To overcome the scalability issue of NW-MMF and NW-PF, we propose a novel power control scheme that is provably scalable. This scheme maximizes the geometric mean (GM) of the per-cell max-min SE. To solve this new optimization problem, we prove that it can be rewritten in a convex optimization form and then solved using standard tools. The simulation results highlight the benefits of our model which is balancing between NW-PF and NW-MMF.

Cell-Free Massive MIMO : Scalability, Signal Processing and Power Control

“…Last but not least, as the law of large numbers comes to play, elegant closedform expressions for the achievable SE can be derived to predict the system performance [20,33,41]. This enables optimization of the spectral and energy efficiency as well as simplification of resource allocation tasks such as power control [20,33,[42][43][44][45][46][47][48][49] and pilot assignment [48,[50][51][52][53].…”

Precoding for TDD and FDD in Measured Massive MIMO Channels

“…For mobile channels where the mean power for different users are often non-equal, the system performance may depend highly on the power allocation scheme. Finding optimum solutions is generally a complex problem depending on the channel, see [26] and references therein. In the current work the water filling procedure is followed, which is optimum for the ZF weights but sub-optimum for MRT and SLNR [22].…”

A pilot allocation method for multi-cell multi-user massive MIMO system

“…The interference caused by transmitting the pilot to- gether with the data will be greatly reduced. In [22], using the theory of structured compressive sensing (CS), the structured subspace pursuit (SSP) algorithm was proposed with low pilot overhead.…”