A Distributed MIMO (Multiple Input Multiple Output) System refers to a wireless communication setup in which multiple transmitter and receiver elements are distributed across different locations or nodes. MIMO technology involves the use of multiple antennas at both the transmitter and receiver sides to improve communication performance by exploiting spatial diversity and multipath propagation.


Enabling Cooperative Hybrid Beamforming in TDD-based Distributed MIMO Systems

Distributed massive MIMO networks are envisioned to realize cooperative multi-point transmission in next-generation wireless systems. For efficient cooperative hybrid beamforming, the cluster of access points (APs) needs to obtain precise estimates of the uplink channel to perform reliable downlink precoding. However, due to the radio frequency (RF) impairments between the transceivers at the two en-points of the wireless channel, full channel reciprocity does not hold which results in performance degradation in the cooperative hybrid beamforming (CHBF) unless a suitable reciprocity calibration mechanism is in place. We propose a two-step approach to calibrate any two hybrid nodes in the distributed MIMO system. We then present and utilize the novel concept of reciprocal tandem to propose a low-complexity approach for jointly calibrating the cluster of APs and estimating the downlink channel. Finally, we validate our calibration technique’s effectiveness through numerical simulation.