Spectral Efficient Precoding Design for Multi-cell Large MU-MIMO System

Abstract

Large scale multiuser multi-input multi-output (MU-MIMO) system is an emerging wireless technology, which can impart huge spectral efficiency, enhanced link reliability, and serves several users simultaneously in the same frequency–time resource. Pilot contamination (PC) is the major bottleneck in achieving the optimum performance of a multi-cell large MU-MIMO system. We propose a new multi-cell block diagonalization-QR-minimum mean square error (M-BD-QR-MMSE) precoding scheme to diminish the effects of pilot contamination in a multi-cell MIMO system. The reduced effects of Pilot contamination result in the enhancement of spectral efficiency for the multi-cell MU-MIMO system. The design of the proposed scheme utilizes block diagonalization (BD) in combination with MMSE precoding that obtains large null space using QR decomposition operation to reduce intercell and intracell interference much efficiently than conventional precoding schemes. The gain in spectral efficiency with the proposed scheme is enhanced through non-universal pilot reuse in contrast to single-cell schemes. Furthermore, the downlink spectral efficiency expression has been derived for a large scale MIMO system, and the same is computed using Monte Carlo simulations to analyze the results. The numerical results depict that the proposed M-BD-QR-MMSE provides a significant improvement in the spectral efficiency in comparison with traditional single-cell MMSE (S-MMSE), regularized zero-forcing (R-ZF), ZF, Maximum ratio transmission (MRT) and multi-cell MMSE (M-MMSE) schemes. The proposed precoding design provides the spectral enhancements of 32.19 and 50.13 bit/s/Hz/cell in comparison to conventional multi-cell MMSE and single-cell MMSE precoding schemes respectively.

KEYWORDS:

• Large scale multiuser MIMO
• Multicell-BD-QR-MMSE precoding
• Pilot contamination
• Pilot reuse
• Intra-cell interference
• Inter-cell interference

Additional information

Notes on contributors

Jagtar Singh

Jagtar Singh received his BTech degree from NIT Kurukshetra, Haryana, MTech from NC College of Engineering, Israna, Panipat and currently pursuing PhD from Guru Jambheshwar University of Science & Technology, Hisar, Haryana, India. His research interest mainly focuses on advances in MIMO technology, digital communication, beyond fourth generation (B4G) wireless communications systems.

Deepak Kedia

Deepak Kedia is working as a professor in the Department of Electronics and Communication Engineering at Guru Jambheshwar University of Science & Technology, Hisar, Haryana, India. He received his BTech degree in electronics & communication engineering from DCRUST, Murthal, MTech degree in electronics & communication engineering from IIT Kharagpur, and PhD from GJUST, Hisar. His research interests are wireless and mobile communications physical layer, CDMA wireless systems, MIMO Systems. He has published over 30 research papers in different journals and conferences. E-mail: [email protected].