Downlink Analysis for the D2D Underlaid Multigroup Multicast Cell-Free Massive MIMO With Low-Resolution ADCs/DACs

Abstract

To fully utilize the scarce spectrum resources, the downlink device-to-device (D2D) underlaid multigroup multicast cell-free massive multi-input multi-output (MIMO) systems is proposed, where the geographically distributed access points (APs) serving both multi-antenna cell-free users (CFUEs) and D2D users (DUEs) pair over the same time/frequency resource blocks. Specially, the low-resolution analog-todigital converters/digital-to-analog converters (ADCs/DACs) are adopted at the AP to effectively reduce hardware damage and energy costs. The imperfect channel state information (CSI) is obtained firstly by the standard minimum mean square error (MMSE), then the lower bounds of the closed-form achievable downlink rates for both CFUEs and DUEs are derived. Aside from that, the sum energy efficiency (EE) is also explored using the established power consumption model. Finally, numerical simulations are assessed to verify the analytical results and provide insights into the effects of the key system parameters. It demonstrates that increasing the number of APs can improve the sum SE, however, the sum EE decreases with the number of the APs sharply. Furthermore, increasing the density of DUEs can significantly improve the system capacity. The findings highlight the significance of the collaborative deployment of D2D and multigroup multicast cell-free massive MIMO technology, which can serve as a valuable reference and guide for the actual deployment of future communication systems.INDEX TERMS Cell-free massive MIMO, D2D, energy efficiency, low-resolution ADCs/DACs, multigroup multicast, spectral efficiency.

Design and Optimization of Hybrid Precoders in Massive MIMO Systems: Leveraging Low-Resolution ADCs/DACs, Reconfigurable Intelligent Surfaces, and Deep Learning Algorithms

“…[16] studied SE and EE optimization with low-precision ADCs. [17][18][19] THz systems, respectively Specific to one-bit DACs. [20][21][22] investigated full-duplex massive MIMO cellular networks, multicast downlink, and mmWave systems, respectively.…”