Clipping noise mitigation with capacity approaching FEC codes for PAPR reduction of OFDM signals

Abstract

By virtue of its simplicity, clipping appears to be one of the most attractive methods to mitigate Peak to Average Power Ratio (PAPR) in OFDM systems. After positioning clipping in a new classification of PAPR reduction methods, this article focuses on the performance of clipped OFDM at low signal to noise ratio, typical of capacity approaching forward error correcting coded systems. A lower bound on the BER performance of clipped coded OFDM is given and shown to be consistent with the genie aided performance of the iterative clipping noise cancellation receiver. Finally, numerical results on the BER performance of a clipped LDPC coded OFDM system are provided. 1

Predistortion performance considering peak to average power ratio reduction in OFDM context

“…Very few publications in literature [12], [13] have studied the distribution of the signal after PAPR reduction in spite of the significant number of proposed techniques [1], [2]. It is well known in literature [13] that after a certain number of subcarriers (64), the OFDM signal is approximated by a complex Gaussian distribution.…”

“…In this section, we will consider the classification of PAPR reduction methods presented in [1] and updated in [2] where most of important PAPR reduction techniques in literature are classified according to some key criteria such as PAPR reduction gain, downward compatibility, BER degradation, power increase, etc.…”

“…They have been in use since many years and include digital predistortion [4]- [6], feedback [5], Linear amplification with non-linear component (LINC) method [3], [5], etc. The large number of PAPR reduction techniques and linearization methods has motivated the publication of a synthesis in [1], [2] gathering methods according to some key criteria.…”

“…In the rest of this paper, we study in section II the distribution of the OFDM signal after PAPR reduction considering the three categories of methods detailed in [2]. After describing the system model, we develop in section III some theoretical formulas regarding the first and the second order moments of the predistortion error.…”

“…We choose the predistortion as a linearization technique and define a predistortion error. Assuming that the baseband OFDM signal is characterized as a complex Gaussian process, we consider the three top categories of PAPR reduction methods presented in [2] and we first study the distribution of the resulted signal. Then, we derive some theoretical expressions of the first and second order moments of the predistortion error and show that the error depends mainly on the PAPR of the signal after PAPR reduction method and on the predistortion quality.…”