Mobility Performance of Scalable Cell-Free Massive MIMO Under Channel Aging and Handover

While cell-free massive MIMO (CF-mMIMO) provides superior throughput performance against traditional cellular networks in static scenarios, the impact of changing mobile channels and serving access point (AP) sets is not yet fully addressed. In this paper we propose an analysis framework for mobile scalable CF-mMIMO taking into account both the channel aging effect and handover cost, by deriving the through-put model of different AP selection methods as functions of UE mobility and AP serving set size. We then use this framework to compare the performance of different AP selection methods for scalable CF-mMIMO, and thereby provide guidelines for future practical mobile network design. Our results show that scalable CF-mMIMO with UE-centric AP selection methods can be superior to the network-centric method only at very low mobility.