305 research outputs found
Frequency-Selective PAPR Reduction for OFDM
We study the peak-to-average power ratio (PAPR) problem in orthogonal
frequency-division multiplexing (OFDM) systems. In conventional clipping and
filtering based PAPR reduction techniques, clipping noise is allowed to spread
over the whole active passband, thus degrading the transmit signal quality
similarly at all active subcarriers. However, since modern radio networks
support frequency-multiplexing of users and services with highly different
quality-of-service expectations, clipping noise from PAPR reduction should be
distributed unequally over the corresponding physical resource blocks (PRBs).
To facilitate this, we present an efficient PAPR reduction technique, where
clipping noise can be flexibly controlled and filtered inside the transmitter
passband, allowing to control the transmitted signal quality per PRB. Numerical
results are provided in 5G New Radio (NR) mobile network context, demonstrating
the flexibility and efficiency of the proposed method.Comment: Accepted for publication as a Correspondence in the IEEE Transactions
on Vehicular Technology in March 2019. This is the revised version of
original manuscript, and it is in press at the momen
A Simplified Scheme of Estimation and Cancellation of Companding Noise for Companded Multicarrier Transmission Systems
Nonlinear companding transform is an efficient method to reduce the high peak-to-average power ratio (PAPR) of multicarrier transmission systems. However, the introduced companding noise greatly degrades the bit-error-rate (BER) performance of the companded multicarrier systems. In this paper, a simplified but effective scheme of estimation and cancellation of companding noise for the companded multicarrier transmission system is proposed. By expressing the companded signals as the summation of original signals added with a companding noise component, and subtracting this estimated companding noise from the received signals, the BER performance of the overall system can be significantly improved. Simulation results well confirm the great advantages of the proposed scheme over other conventional decompanding or no decompanding schemes under various situations
Optimizing multi-antenna M-MIMO DM communication systems with advanced linearization techniques for RF front-end nonlinearity compensation in a comprehensive design and performance evaluation study
The study presented in this research focuses on linearization strategies for compensating for nonlinearity in RF front ends in multi-antenna M-MIMO OFDM communication systems. The study includes the design and evaluation of techniques such as analogue pre-distortion (APD), crest factor reduction (CFR), multi-antenna clipping noise cancellation (M-CNC), and multi-clipping noise cancellation (MCNC). Nonlinearities in RF front ends can cause signal distortion, leading to reduced system performance. To address this issue, various linearization methods have been proposed. This research examines the impact of antenna correlation on power amplifier efficiency and bit error rate (BER) of transmissions using these methods. Simulation studies conducted under high signal-to-noise ratio (SNR) regimes reveal that M-CNC and MCNC approaches offer significant improvement in BER performance and PA efficiency compared to other techniques. Additionally, the study explores the influence of clipping level and antenna correlation on the effectiveness of these methods. The findings suggest that appropriate linearization strategies should be selected based on factors such as the number of antennas, SNR, and clipping level of the system
Performance Analysis of OFDM with Peak Cancellation Under EVM and ACLR Restrictions
This paper presents performance analysis of an adaptive peak cancellation
method to reduce the high peak-toaverage power ratio (PAPR) for OFDM systems,
while keeping the out-of-band (OoB) power leakage as well as an in-band
distortion power below the pre-determined level. In this work, the increase of
adjacent leakage power ratio (ACLR) and error vector magnitude (EVM) are
estimated recursively using the detected peak amplitude. We present analytical
framework for OFDM-based systems with theoretical bit error rate (BER)
representations and detection of optimum peak threshold based on predefined EVM
and ACLR requirements. Moreover, the optimum peak detection threshold is
selected based on the oretical design to maintain the predefined distortion
level. Thus, their degradations are automatically restricted below the
pre-defined levels which correspond to target OoB radiation. We also discuss
the practical design of peak-cancellation (PC) signal with target OoB radiation
and in-band distortion through optimizing the windowing size of the PC signal.
Numerical results show the improvements with respect to both achievable bit
error rate (BER) and PAPR with the PC method in eigen-beam space division
multiplexing (E-SDM) systems under restriction of OoB power radiation. It can
also be seen that the theoretical BER shows good agreements with simulation
results
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