259 research outputs found
A Comparison of Several Gradient Based Optimization Algorithms for PAPR Reduction in OFDM Systems
International audienceThe 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 Quasi-Newton 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
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
OFDM PAPR reduction for image transmission using improved tone reservation
High peak to average power ration (PAPR) in orthogonal frequency division multiplexing (OFDM) is an important problem, which increase the cost and complexity of high power amplifiers. One of the techniques used to reduce the PAPR in OFDM system is the tone reservation method (TR). In our work we propose a modified tone reservation method to decrease the PAPR with low complexity compared with the conventional TR method by process the high and low amplitudes at the same time. An image of size 128×128 is used as a source of data that transmitted using OFDM system. The proposed method decrease the PAPR by 2dB compared with conventional method with keeping the performance unchanged. The performance of the proposed method is tested with several numbers of subcarriers; we found that the PAPR is reduced as the number of subcarriers decreased
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