Semi-Blind Spatial Equalisation for MIMO Channels with Quadrature Amplitude Modulation

Abstract

Abstract-Semi-blind spatial equalisation is considered for multiple-input multiple-output (MIMO) systems that employ high-throughput quadrature amplitude modulation scheme. A minimum number of training symbols, equal to the number of transmitters, are first utilised to provide a rough least squares channel estimate of the system's MIMO channel matrix for the initialisation of the spatial equalisers' weight vectors. A constant modulus algorithm aided soft decision-directed blind algorithm is then employed to adapt the spatial equalisers. This semiblind scheme has a very-low computational complexity, and it converges fast to the minimum mean-square-error spatial equalisation solution as demonstrated in our simulation study.

Hybrid methods in MIMO blind equalization and source separation

“…In practice, we use the stochastic gradient descent method to minimize the cost function (3). As a result, the equalizer coefficients after dropping E{.}…”

“…The ability of the system to approach the MIMO capacity strongly depends on the accuracy of channel estimation. Most papers on MIMO channel estimation and symbol recovery assume flat fading channels [3], [4], [7]. In this case, each of the received signal can be viewed as a linear mixture of all transmitted signals.…”