Abstract
This paper considers a hybrid beamforming massive multiple-input multiple-output (MIMO) system operating in time-division duplex (TDD) mode. We investigate the combined impacts of quantized phase shifters (QPSs), channel non-reciprocity and channel estimation errors on the achievable spectral efficiency (SE) of the considered system. We first introduce an equivalent hybrid beamforming structure, based on which, a generic and practical channel non-reciprocity model is built for massive MIMO systems with hybrid structure. This model jointly considers the mismatch between transceiver and receiver circuits, as well as the mutual coupling between antennas. Then we derive the generic expression of achievable SE for both the ideal phase shifters (IPSs) and QPSs cases. Furthermore, the closed-form expressions of SE are derived for IPSs and QPSs cases, respectively. The asymptotic performance in large antenna regime is also analyzed based on these expressions. Simulation results demonstrate the validity and accuracy of the derived analytical expressions. In addition, results show that the phase quantization and channel non-reciprocity both contributes to the SE degradation and the detrimental effects cannot be canceled completely even in the large-antenna regime.
Highlights
Massive multiple-input-multiple-output (MIMO) is a key enabler for the 5th generation cellular networks (5G) [1]
The channel coherence time is set to 1 ms, which is the duration of a subframe in 3GPP LTE/LTE-A/NR networks [34], [35]
Simulation results showed a perfect match of analytical and simulated results, which indicates that our analytical expressions can be used to effectively evaluate the performance of the considered system
Summary
Massive multiple-input-multiple-output (MIMO) is a key enabler for the 5th generation cellular networks (5G) [1]. Different from [16]–[19], an relative calibration method is proposed for the TDD hybrid beamforming massive MIMO systems in [20] These works don’t provide an analytical framework to evaluate the impact of channel non-reciprocity. In this paper, we analyze the achievable SE of TDD hybrid beamforming massive MIMO systems under the compound impacts of QPSs, channel non-reciprocity, and estimation errors. We derive the generic expressions of the achievable SINR and SE for both IPSs and QPSs based massive MIMO systems, in the presence of quantization level, channel non-reciprocity and estimation errors. We quantify and compare the SE degradation in the presence of quantization level, channel non-reciprocity and estimation errors by simulations, and provide insights for the implementation of hybrid beamforming massive MIMO systems.
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