PAPR and the Density of Information Bearing Signals in OFDM

Holger Boche,Brendan Farrell

doi:10.1155/2011/561356

Holger Boche, Brendan Farrell

Open Access

https://doi.org/10.1155/2011/561356

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Abstract

We address the peak-to-average power ratio (PAPR) of transmission signals in OFDM and consider the performance of tone reservation for reduction of the PAPR. Tone reservation is unique among methods for reducing PAPR, because it does not affect information bearing coefficients and involves no additional coordination of transmitter and receiver. It is shown that if the OFDM system always satisfies a given peak-to-average power ratio constraint, then the efficiency of the system, defined as the ratio of the number of tones used for information to the entire number of tones used, must converge to zero as the total number of tones increases. More generally, we investigate and provide insight into a tradeoff between optimal signal and information properties for OFDM systems and show that it is necessary to use very small subsets of the available signals to achieve PAPR reduction using tone reservation.

Highlights

OFDM is one of today’s most widely used and promising information transmission schemes
With Theorem 2 we show that if it is required that the peak-to-average power ratio remains bounded, the efficiency of the OFDM system converges to zero as the system size increases
The approach to the peak-to-average power ratio (PAPR) reduction problem presented here has two parts: first, we showed an equivalence between solvability and a norm relation, and we considered cases when we could violate or satisfy the norm relation

Summary

Introduction

OFDM is one of today’s most widely used and promising information transmission schemes. Given a set of coefficients for the tones in the information set, coefficients are chosen for tones in the compensation set, so that the peak value of the combined signal is reduced. The location of these two sets remains fixed for all codewords and over all uses of the channel. Of the handful of methods to reduce PAPR, tone reservation is robust and canonical This is because the only information that the receiver requires is the location of the information set. There we give a short discussion of transmission schemes for fifth generation cellular networks, as well as nonorthogonal transmission systems and their PAPR behavior

The Finite Set OFDM Case

The Infinite Set Case

The Discrete Fourier Case

Discussion and Conclusion