Non-reused pilot design for large-scale multi-cell multiuser MIMO system

We propose a novel time-shift pilot scheme to mitigate the pilot contamination in large-scale multicell multiuser MIMO (LS-MIMO) systems. In the proposed scheme, the length of the uplink training pilot sequence is equal to the cell number; that is to say, the same pilot sequence is used within a cell, while for different cells, pilot sequences are mutually orthogonal. Moreover, users within a cell transmit the same pilot sequence in a time-shift manner during the channel estimation stage and in this way all user terminals’ channel state information can be estimated without contamination. The asymptotic channel orthogonality is studied in the LS-MIMO system, with which the mutual interference among cells caused by data and pilot sequences can be cancelled with the successive interference cancellation (SIC) method. We explore the superiority of the proposed scheme in channel coefficient estimation, uplink data detection, and downlink data transmission steps. Theoretical analysis and simulation results demonstrate that the proposed time-shift pilot design can alleviate the pilot contamination problem and improve the performance of the considered system significantly compared with the popular orthogonal pilots.

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Main-Branch Structure Iterative Detection Using Approximate Message Passing for Uplink Large-Scale Multiuser MIMO Systems

International Journal of Antennas and Propagation ◽

10.1155/2016/2832584 ◽

2016 ◽

Vol 2016 ◽

pp. 1-12

Author(s):

Qifeng Zou ◽

Xuezhi Tan ◽

Mei Liu ◽

Lin Ma

Keyword(s):

Message Passing ◽

Communication Systems ◽

Orthogonal Frequency Division Multiplexing ◽

Large Scale ◽

Mimo Systems ◽

Mimo System ◽

Detection Methods ◽

Iterative Detection ◽

Multiuser Mimo ◽

Approximate Message Passing

The emerging large-scale/massive multi-input multioutput (MIMO) system combined with orthogonal frequency division multiplexing (OFDM) is considered a key technology for its advantage of improving the spectral efficiency. In this paper, we introduce an iterative detection algorithm for uplink large-scale multiuser MIMO-OFDM communication systems. We design a Main-Branch structure iterative turbo detector using the Approximate Message Passing algorithm simplified by linear approximation (AMP-LA) and using the Mean Square Error (MSE) criterion to calculate the correlation coefficients between main detector and branch detector for the given iteration. The complexity of our method is compared with other detection algorithms. The simulation results show that our scheme can achieve better performance than the conventional detection methods and have the acceptable complexity.

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A low computational design of multiuser MIMO system using large scale array antenna

2014 International Conference and Workshop on the Network of the Future (NOF) ◽

10.1109/nof.2014.7119761 ◽

2014 ◽

Author(s):

Tetsuki Taniguchi ◽

Yoshio Karasawa

Keyword(s):

Large Scale ◽

Mimo System ◽

Computational Design ◽

Array Antenna ◽

Multiuser Mimo

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Performance of ZF and CB Precoding Techniques for Large-Scale MU-MIMO System

International Journal of Recent Technology and Engineering - 2 ◽

10.35940/ijrte.b3283.078219 ◽

2019 ◽

Vol 8 (2) ◽

pp. 5529-5536

Keyword(s):

Energy Efficiency ◽

Spectral Efficiency ◽

Large Scale ◽

Mimo System ◽

New Technology ◽

Vital Role ◽

Base Station ◽

Multiuser Mimo ◽

Channel State ◽

User Interference

Large Scale Multi User-MIMO (MU-MIMO) is a key technology with reference to 5G to achieve higher spectrum as well as energy efficiency. The new technology refers to the use of a large number of antennas at the base station serving many user terminals in the same time and frequency resource allowing the channel vectors nearly orthogonal as a result, there is a reduction in inter-user interference and users may be served with the significant data rate. The linear precoding techniques play a vital role in the reduction of interference among users and cells. In this paper, we have derived, analyzed and compared two important precoding techniques i.e. Zero-forcing (ZF) and Conjugate beamforming (CB) for large-scale multiuser-MIMO. We analyze these precoding techniques with respect to spectral efficiency and downlink power with imperfect channel state information (CSI) as well as with perfect CSI. It is shown that ZF performs better as compared to CB precoding for achieving higher spectral efficiency and requires lower downlink power. CB outperforms the ZF in terms of downlink transmit power when there is a requirement to achieve low spectral efficiency and also for celledge users, hence energy efficient in these cases. It is shown from simulation results that ZF precoding is the better choice for attaining higher spectral and energy efficiency for a large scale multiuser-MIMO communication system.

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