Amirkabir University of Technology AUT Journal of Electrical Engineering 2588-2910 53 2 2021 12 01 Designing Cost- and Energy-Efficient Cell-free Massive MIMO Network with Fiber and FSO Fronthaul Links 159 170 4286 10.22060/eej.2021.19273.5388 EN Pouya Agheli Amirkabir University of Technology Mohammad Javad Emadi Amirkabir university of technology Hamzeh Beyranvand Amirkabir University of Technology 0000-0001-7013-5865 Journal Article 2020 11 17 The emerging cell-free massive multiple-input multiple-output (CF-mMIMO) is a promising scheme to tackle the capacity crunch in wireless networks. Designing the optimal fronthaul network in the CF-mMIMIO is of utmost importance to deploy a cost and energy-efficient network. In this paper, we present a framework to optimally design the fronthaul network of CF-mMIMO utilizing optical fiber and free space optical (FSO) technologies. We study an uplink data transmission of the CF-mMIMO network, wherein each of the distributed access points (APs) is connected to a central processing unit (CPU) through a capacity-limited fronthaul, which could be the optical fiber or FSO. Herein, we have derived achievable rates and studied the network's energy efficiency in the presence of power consumption models at the APs and fronthaul links. Although an optical fiber link has a larger capacity, it consumes less power and has a higher deployment cost than tan FSO link. For a given total number of APs, the optimal number of optical fiber and FSO links and the optimal capacity coefficient for the optical fibers are derived to maximize the system's performance. Finally, the network's performance is investigated through numerical results to highlight the effects of different types of optical fronthaul links. https://eej.aut.ac.ir/article_4286_fa612be4940bae15b019b36f9282c5ab.pdf