Blind Channel Estimation for MIMO Systems via Variational Inference

TL;DR

This paper introduces a neural network-based variational inference method for blind MIMO channel estimation that reduces pilot overhead and achieves performance comparable to traditional pilot-assisted techniques.

Contribution

It presents a novel variational inference framework for blind MIMO channel estimation, eliminating the need for pilot symbols and improving efficiency.

Findings

Performance close to pilot-assisted methods in channel estimation error

Achieves similar symbol error rates without pilot symbols

Reduces pilot overhead in MIMO systems

Abstract

In this paper, we investigate the blind channel estimation problem for MIMO systems under Rayleigh fading channel. Conventional MIMO communication techniques require transmitting a considerable amount of training symbols as pilots in each data block to obtain the channel state information (CSI) such that the transmitted signals can be successfully recovered. However, the pilot overhead and contamination become a bottleneck for the practical application of MIMO systems with the increase of the number of antennas. To overcome this obstacle, we propose a blind channel estimation framework, where we introduce an auxiliary posterior distribution of CSI and the transmitted signals given the received signals to derive a lower bound to the intractable likelihood function of the received signal. Meanwhile, we generate this auxiliary distribution by a neural network based variational inference framework, which is trained by maximizing the lower bound. The optimal auxiliary distribution which approaches real prior distribution is then leveraged to obtain the maximum a posterior (MAP) estimation of channel matrix and transmitted data. The simulation results demonstrate that the performance of the proposed blind channel estimation method closely approaches that of the conventional pilot-aided methods in terms of the channel estimation error and symbol error rate (SER) of the detected signals even without the help of pilots.