scholarly journals Optimal precoder design for non-regenerative multiple-input multiple-output cognitive relay systems with perfect and imperfect channel state information

2013 ◽  
Vol 15 (8) ◽  
pp. 1213-1224 ◽  
Author(s):  
Quanzhong Li ◽  
Liping Luo ◽  
Jiayin Qin
Keyword(s):  
Channel State Information ◽  
Multiple Input Multiple Output ◽  
Imperfect Channel State Information ◽  
Channel State ◽  
State Information ◽  
Relay Systems ◽  
Multiple Input ◽  
Precoder Design ◽  
Input Multiple Output

scholarly journals Power Optimization of Tilted Tomlinson-Harashima Precoder in MIMO Channels with Imperfect Channel State Information

2013 ◽  
Vol 2013 ◽  
pp. 1-6
Author(s):  
Hossein Khaleghi Bizaki ◽  
Morteza Khaleghi Hojaghan ◽  
Seyyed Mohammad Razavizadeh
Keyword(s):  
Channel State Information ◽  
Communication Systems ◽  
Estimation Error ◽  
Multiple Input Multiple Output ◽  
Channel Estimation Error ◽  
Imperfect Channel State Information ◽  
Mimo Channels ◽  
Channel State ◽  
State Information ◽  
Input Multiple Output

This paper concentrates on the designing of a robust Tomlinson-Harashima Precoder (THP) over multiple-input multiple-output (MIMO) channels in wireless communication systems with assumption of imperfect channel state information (CSI) at the transmitter side. With the assumption that the covariance matrix of channel estimation error is available at the transmitter side, we design a THP that presents robustness against channel uncertainties. In the proposed robust THP, the transmit power is further minimized by using the Tilted constellation concept. This power minimization reduces the interchannel Interference (ICI) between subchannels and, furthermore, recovers some part of the THP's power loss. The bit error rate (BER) of the proposed system is further improved by using a power loading technique. Finally, the simulation results compare the performance of our proposed robust THP with a conventional MIMO-THP.

Investigation of low-density parity check codes concatenated multi-user massive multiple-input multiple-output systems with imperfect channel state information

2020 ◽  
pp. 154851292096863
Author(s):  
Lokesh Bhardwaj ◽  
Ritesh Kumar Mishra ◽  
Ravi Shankar
Keyword(s):  
Spectral Efficiency ◽  
Multiple Input Multiple Output ◽  
Low Density ◽  
Parity Check ◽  
Imperfect Channel State Information ◽  
Channel State ◽  
State Information ◽  
Low Density Parity Check ◽  
Multiple Input ◽  
Input Multiple Output

In this era of communication technology, it is desirable to increase the data rate while minimizing the error to improve the system’s reliability. One of these techniques is massive multiple-input multiple-output (mMIMO), which increases the spectral efficiency by providing the data to multiple users simultaneously through spatial multiplexing. The mMIMO system processes the received signal by prior estimation of the channel, which has a finite variance leading to imperfect channel state information (ICSI) at the receiver. In the fifth-generation technology, spectral efficiency using mMIMO may decrease as the number of subscribers increases, resulting in more interference and affecting system capacity. The ICSI provides another challenge, as the processed data at the receiver’s output may now be more erroneous. Thus, this article provides an insight into the impact of an increase in the number of users on the variation in bit error rate with the signal-to-noise ratio in multi-user mMIMO (MU-mMIMO) and low-density parity check (LDPC) codes concatenated MU-mMIMO systems having ICSI at the receiver for quadrature amplitude modulation (QAM) and 16-QAM as modulation techniques. It has been shown that the performance of the concatenated scheme outperforms the conventional mMIMO system.

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