Mitigation of UE Antenna Calibration Errors via Differential STBC in Cell-Free Massive MIMO

TL;DR

This paper proposes using differential space-time block coding to mitigate antenna calibration errors at user equipment in cell-free massive MIMO systems, enabling reliable downlink communication without explicit calibration.

Contribution

The study introduces a DSTBC-based method that compensates for UE antenna calibration impairments in CF-mMIMO, eliminating the need for explicit phase knowledge.

Findings

DSTBC effectively mitigates antenna phase offsets.

Near-coherent performance restored in simulations.

Reliable downlink communication without UE calibration.

Abstract

This letter investigates the use of differential space-time block coding (DSTBC) to address antenna array calibration impairments at multi-antenna user equipment (UE) in the downlink (DL) of cell-free massive MIMO (CF-mMIMO) systems. We show that, by exploiting DSTBC, reliable DL communication can be achieved without explicit UE-side calibration or channel phase knowledge. Simulation results demonstrate that the proposed DSTBC-based transmission effectively mitigates the impact of antenna-dependent phase offsets, restoring near-coherent performance in CF-mMIMO networks.