A comparison of several gradient based optimization algorithms for PAPR reduction in OFDM systems

Abstract

Abstract-The aim of this paper is to evaluate and compare different optimization algorithms for Peak to Average Power Ratio (PAPR) reduction in Orthogonal Frequency Division Multiplexing (OFDM) systems. Based on Tone Reservation (TR) method, we exploit the unused subcarriers of the studied standard to generate the peak canceling signal without data rate loss. Gradient, Conjugate-Gradient with two directions search and QuasiNewton methods have been investigated and evaluated on the basis of spectral regrowth, convergence speed and ability to improve the high peak-to-average reduction in multicarriers systems. As an example, the simulations are performed in the case of Local Area Network WLAN (IEEE 802.11a standard). Simulation results show that a PAPR reduction gain around 3 dB can be achieved.

New technique combining the Tone Reservation method with Clipping technique to reduce the Peak-to-Average Power Ratio

“…It is an iterative method just like the method of the gradient, but it uses an algorithm so that the direction of research is optimal. This direction is determined by the gradient at the point X n and the gradient of the previous point X n−1 [17]. For the first iteration, the chosen direction is the negative gradient:…”

“…In this paper, our contribution called (TRCL) is a new method based on the combination of two methods to reduce PAPR, TR [15], [16] with Conjugate Gradient Optimization algorithm [17], [18] and CL [5], [6]. These two methods present a certain complementarity: the TR method based on the addition of signal is one of the methods having the property of downward compatibility and improving the performance of EVM and BER due to their low degradation and their low intake of supplementary computational complexity, but its performance remains limited because of the reduced number of free subcarriers, while the CL is very simple of those known this day and theoretically allows an unlimited clipping of the signal but unfortunately with a degradation of all the communication criteria and a decrease in performance caused by a loss of some information.…”

Estimation of the noise immunity of troposphere communication systems with OFDM signals and available ways to increase ones bit error ratio

“…Disadvantages [7]: high sensitivity to frequency shifts and phase fluctuations; great peak to averaged factor value PAPR decrease energy efficiency, but there exists algorithms for one decreasing [11].…”

“…Optimized algorithms for OFDM modem creation, is explored in [7,11], variety of mobile devices, modems, routers for WiFi and 4G networks lead to possibility to develop OFDM modems for tropospheric communication system on FPGA. One powerfull solution there is Kintex-7 board.…”

“…There adaptive algorithms are used [7,11] to the best performance with a maximal speed and noise-immunity, and developing of new ones -is the third direction to improve OFDM system. Subcarriers number about 2 10 leads to the best speed comparing to 1, 3 or four subcarriers [5].…”