# Beamspace Channel Estimation for Millimeter Wave Massive MIMO System with Hybrid Precoding and Combining

## TL;DR

This paper proposes a beamspace channel estimation framework for mmWave massive MIMO systems with hybrid precoding, introducing three new schemes that outperform existing methods in efficiency and accuracy.

## Contribution

The paper introduces three novel beamspace channel estimation schemes and a comprehensive framework for hybrid precoding and combining in mmWave massive MIMO systems.

## Key findings

- Proposed schemes outperform existing methods in estimation accuracy.
- Total training time slots are significantly reduced.
- Simulation results approach ideal performance levels.

## Abstract

In this paper, a framework of beamspace channel estimation in millimeter wave (mmWave) massive MIMO system is proposed. The framework includes the design of hybrid precoding and combining matrix as well as the search method for the largest entry of over-sampled beamspace receiving matrix. Then based on the framework, three channel estimation schemes including identity matrix approximation (IA)-based scheme, scattered zero off-diagonal (SZO)-based scheme and concentrated zero off-diagonal (CZO)-based scheme are proposed. These schemes together with the existing channel estimation schemes are compared in terms of computational complexity, estimation error and total time slots for channel training. Simulation results show that the proposed schemes outperform the existing schemes and can approach the performance of the ideal case. In particular, total time slots for channel training can be substantially reduced.