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

PAPR reduction using iterative clipping/filtering and ADMM approaches for OFDM-based mixed-numerology systems

Mixed-numerology transmission is proposed to support a variety of communication scenarios with diverse requirements. However, as the orthogonal frequency division multiplexing (OFDM) remains as the basic waveform, the peak-to average power ratio (PAPR) problem is still cumbersome. In this paper, based on the iterative clipping and filtering (ICF) and optimization methods, we investigate the PAPR reduction in the mixed-numerology systems. We first illustrate that the direct extension of classical ICF brings about the accumulation of inter-numerology interference (INI) due to the repeated execution. By exploiting the clipping noise rather than the clipped signal, the noise-shaped ICF (NS-ICF) method is then proposed without increasing the INI. Next, we address the in-band distortion minimization problem subject to the PAPR constraint. By reformulation, the resulting model is separable in both the objective function and the constraints, and well suited for the alternating direction method of multipliers (ADMM) approach. The ADMM-based algorithms are then developed to split the original problem into several subproblems which can be easily solved with closed-form solutions. Furthermore, the applications of the proposed PAPR reduction methods combined with filtering and windowing techniques are also shown to be effective

FPGA-Based Realisation of SDR with OFDM Tranceiver

Software-defined radio architecture is the key point of next generation communication systems in which some of the functional units are designed as software on a reconfigurable processor. This paper proposes the physical layer architecture of SDR with modified orthogonal frequency division multiplexing (OFDM). One of the main drawbacks of OFDM is that its high peak-to-average reduction (PAPR) ratio. The PAPR can be reduced using filtering and adaptive peak windowing method with Kaiser window. The adaptive window method finds the positions of maximum peak values using a peak detector in the signal and applies the window function with variable parameter. The radix 2 scalable N point FFT algorithm is used in the system. The mapping of the information signal is done with BPSK, PSK, and 16 QAM modulation. According to the signal-to- noise ratio (SNR) value, the type of modulation can be selected. Decoding of the OFDM signal in the receiver is done with Viterbi decoding algorithm. The communication system simulation is done in MATLAB and the baseband operations are implemented on Xilinx FPGA.Defence Science Journal, Vol. 65, No. 3, May 2015, pp.233-239, DOI: http://dx.doi.org/10.14429/dsj.65.601

Performance of PAPR Reduction Techniques for MIMO-OFDM Systems in 4G Wireless Communication

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Active Constellation Extension for Peak Power Reduction Based on Positive and Negative Iterations in OFDM Systems

Traditional active constellation extension (ACE) techniques iterate under a further and further away from decision boundary constraint to find distortions for peak-to-average power ratio (PAPR) reduction, which may stop the solution on suboptimal points because it's not permitted to go back when running into a suboptimum direction. In this paper, we present a novel ACE technique by iterating in both positive and negative directions, referring to distortions found in the last iteration. During iterations, optimization variations are changed from normally used extra distortions on the last estimates to the primitive OFDM signal, which can eliminate correlations between magnitudes and phases of complex distortions and finally give an analytic solution based on orthogonal projection. By making iterations run in positive and negative directions, this algorithm can find distortions to reduce PAPR more, compared with existing methods. Simulation results show that significant improvement can be achieved either for pure ACE or TR assisted ACE method, especially under higher-order modulation schemes

A Review on PAPR Reduction in Perspective of BER Performance in MIMO-OFDM Based Next Generation Wireless Systems.

Today, high speed and trustworthy wireless communication over mobile is the requirement of society. As the mobile applications and the users are rapidly increasing, it is obligatory to have more reliable, high speed wireless network with high throughput, which will combat the disadvantages in existing system in this multiuser environment. In wireless system the received signal may be corrupted due to noise and interferences such as ‘inter symbol interference’ and ‘inter carrier interference’ when subjected to multi-path fading. Also the performance the system may be affected due to poor ‘bit error rate’ and high ‘peak to average power ratio’ value, which further affect the signal power and spectral efficiency of transmitted signal. The blend of ‘orthogonal frequency division multiplexing’ and ‘multi input multi output’ antenna system referred as MIMO-OFDM system, which offers the improvement in quality of service and higher throughput to satisfy the tomorrow’s need. This review article mainly focuses on various technologies adopted by different researchers for enhancing the ‘bit error rates’, ‘peak to average power ratio’, ‘signal to noise ratio’ and ‘spectral efficiency’ performances in wireless systems. We continue by highlighting the limitations and comparing results of conventional methods, schemes and algorithms proposed by different researchers.  We also focus on the multiple antenna system (MIMO), which is designed for future multiuser environment to enhance the capacity or to have high throughput along with good quality services

PAPR Reduction and Sidelobe Suppression in Cognitive OFDM - A Survey

Cognitive radio (CR) is one of the key technology providing a new way to enhance the utilization of available spectrum effectively. The multicarrier modulation (MCM) technique which is widely used is Orthogonal Frequency Division Multiplexing (OFDM) system, is an excellent choice for high data rate application. The main two limitations of this technology is the high peak-to-average power ratio (PAPR) of transmission signal and large spectrum sidelobe. This article describes some of the important PAPR reduction techniques and sidelobe suppression techniques