Performance of Assigning Pilot Sequences in Cell Free Massive MIMO under SINR Constraints

In this paper, we consider the uplink (UL) of Cell-Free (CF) Massive MIMO system where a large number of service antennas act as access points (APs), serving distributed users. APs have multiple antennas, while each user has only one antenna. The target is to minimize users’ power consumption under imperfect channel state information (CSI) by optimally allocating the UL transmit power to each user, while maintaining the Quality of Service (QoS) for every user in the network. We investigate also the effect of assigning pilot sequences to the SE performance, when the system analysis is performed under maximum ratio combining. The results are derived by an offline training phase using Rayleigh fading channels. It has been indicated that joint pilot assignment and power allocation have a positive impact on the maximum network QoS value as well as overall power consumption of users in the system.