A Covariance-Based Hybrid Channel Feedback in FDD Massive MIMO Systems

Abstract

In this paper, a novel covariance-based channel feedback mechanism is investigated for frequency division duplexing (FDD) massive multi-input multi-output (MIMO) systems. The concept capitalizes on the notion of user statistical separability which was hinted in several prior works in the massive antenna regime but has not fully exploited so far. We propose a hybrid statistical-instantaneous feedback mechanism where the users are separated into two classes of feedback design based on their channel covariance. Under the hybrid framework, each user either operates on a statistical feedback mode or quantized instantaneous channel feedback mode. The key challenge lies in the design of a covarianceaware classification algorithm which can handle the complex mutual interactions among all users. The classification is derived from rate bound principles and a precoding method is also devised under the mixed statistical and instantaneous feedback model. Simulations are performed to validate our analytical results and illustrate the sum rate advantages of the proposed feedback scheme under a global feedback overhead constraint.

Performance Analysis of Channel Extrapolation in FDD Massive MIMO Systems

“…[17] similarly proposes an angle-of-departure (AoD) adaptive subspace codebook to reduce channel feedback overhead. In [18], a hybrid statistical-instantaneous feedback mechanism where the users are separated into two classes of feedback design based on their channel covariance. Ref.…”

Error probability analysis for ultra-massive MIMO system and near-optimal signal detection

“…where Q(•) is defined as digital demodulation function. According to (4)- (5), it is obvious that the complexity of the MF detector is extremely low, but it is only able to support a low number of users in the context of massive MIMO configurations [1], resulting in wasting some resource.…”

“…Massive multiple-input multiple-output (MIMO) transmission technique, which employs a large num-ber of antennas at the base station (BS) to serve numerous users, has been deemed a key technology for the fifth generation (5G) communication [1][2][3][4][5][6][7]. With the development of 5G beyond communication, the number of mobile users will be further increased significantly, so that the existing massive MIMO technique is unable to meet future mobile users' pursuit of speed and capacity.…”

Spatially Asymptotic Behavior of Structured Covariance Matrix Estimation for Massive MIMO

“…Antenna correlation can be desirable as it provides structure in signal statistics which can, in turn, be used to mitigate multiuser interference or pilot contamination in massive MIMO systems [1] [2]. More generally, the spatial covariance matrix can be used in DoA estimation [3], channel estimation and feedback [4], [5], user scheduling [6], and precoding [7]. Hence, the efficiency of a spatial covariance matrix estimation method can play an important role in improving the performance of massive MIMO techniques.…”