Cell-free networks

Abstract

Future wireless networks will have to manage billions of devices at once, and each one needs a high throughput to serve a range of applications, including speech, real-time video, high-definition video, and others. Due to the excessively high interference levels and poor performance of user equipment (UEs) at the cell boundary, cellular networks are unable to handle such heavy connections. Additionally, human users are the primary target audience for conventional cellular networks. The Internet of Things, the Internet of Everything, Smart X, and other machine-type communication systems are projected to play a significant part in future wireless networks. The main difficulty facing machine-type communications is connecting billions of units in an effective and scalable manner. Cellular topologies with centralized technology do not seem to operate in such scenarios because each cell can only support a certain number of UEs. In order to serve numerous UEs and make distributed signal processing simpler, cell-free (CF) networks with decentralized technologies have been suggested. The combination of CF networks and massive MIMO (mMIMO) technology yields a new concept: Cell-Free Massive MIMO (CF mMIMO) Networks. This chapter gives an overview of Cell-Free Massive MIMO Networks and the underlying technologies. Thus, CF mMIMO is a disruptive technology for the next generations of densified wireless systems. Since cell-free massive MIMO is a developing technology, a number of issues and questions still need to be tackled before rolling out it into practice. In this chapter, we will highlight the various issues concerning CF mMIMO with clear explanation. We will divulge into issues like signal processing schemes, channel estimation, pilot assignment schemes, power controls, and access point (AP) selection schemes among others.