SPAWC 2019, 20th IEEE International Workshop on Signal Processing Advances in Wireless Communications, 2-5 July 2019, Cannes, France
Time Division Duplexing (TDD) Massive MIMO (MaMIMO) relies on channel reciprocity to derive the channel state information at the transmit side (CSIT) from the uplink (UL) channel estimates. This reciprocity is impacted by the transmit and receive front ends which are non-reciprocal and hence a calibration is required to obtain the downlink (DL) channels from the UL channel estimates. The Cramer-Rao Bound
(CRB) for reciprocity calibration and an optimal algorithm were derived in ,  recently. In this work, we extend this and derive a generalized CRB that applies to both coherent and non-coherent calibration schemes (introduced in ). More importantly, we provide original mean squared error analysis for the commonly used Least-Squares (LS) estimator under different parameter constraints, and relate it to the CRB. Finally, we
compare some antenna grouping strategies for calibration based on their CRB.
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