Ubiquitous Cell-Free Massive MIMO Communications

TL;DR

Ubiquitous cell-free Massive MIMO is a distributed wireless technology that enhances network performance by overcoming inter-cell interference and providing macro-diversity, addressing practical deployment challenges for future 5G and beyond networks.

Contribution

This paper introduces the concept of ubiquitous cell-free Massive MIMO, highlighting its advantages over traditional Massive MIMO and discussing practical deployment issues.

Findings

Potential for improved spectral and energy efficiency.

Enhanced macro-diversity and interference mitigation.

Discussion on deployment challenges and back-hauling overhead.

Abstract

Since the first cellular networks were trialled in the 1970s, we have witnessed an incredible wireless revolution. From 1G to 4G, the massive traffic growth has been managed by a combination of wider bandwidths, refined radio interfaces, and network densification, namely increasing the number of antennas per site. Due its cost-efficiency, the latter has contributed the most. Massive MIMO (multiple-input multiple-output) is a key 5G technology that uses massive antenna arrays to provide a very high beamforming gain and spatially multiplexing of users, and hence, increases the spectral and energy efficiency. It constitutes a centralized solution to densify a network, and its performance is limited by the inter-cell interference inherent in its cell-centric design. Conversely, ubiquitous cell-free Massive MIMO refers to a distributed Massive MIMO system implementing coherent user-centric transmission to overcome the inter-cell interference limitation in cellular networks and provide additional macro-diversity. These features, combined with the system scalability inherent in the Massive MIMO design, distinguishes ubiquitous cell-free Massive MIMO from prior coordinated distributed wireless systems. In this article, we investigate the enormous potential of this promising technology while addressing practical deployment issues to deal with the increased back/front-hauling overhead deriving from the signal co-processing.