Abstract
A well-known drawback of orthogonal frequency-division multiplexing (OFDM) is its signal with high peak-to-average power ratio (PAPR). Among a number of PAPR reduction techniques, clipping and filtering (CAF) is the simplest approach, which effectively reduces the PAPR of band-limited OFDM signals at the cost of increasing in-band distortion. In order to mitigate the performance degradation caused by the in-band distortion, several iterative distortion recovery techniques have been proposed in the literature, and they are largely classified into time-domain (TD) and frequency-domain (FD) compensation approaches: The former and latter are represented by the decision-aided reconstruction (DAR) and clipping noise cancellation (CNC), respectively. To date, however, their theoretical performance limits have not been studied. In this work, we revisit the performance limits of CAF and derive a closed-form signal-to-distortion power ratio (SDR) expression. Furthermore, we introduce a time-domain distortion model for characterizing the OFDM signal with CAF, based on which we make performance comparison between the two compensation approaches. Theoretical analysis and simulations in terms of their achievable symbol error rate (SER) reveal that, unlike the FD counterpart, the TD compensation may suffer from unrecoverable distortion when filtering after clipping is applied at the transmitter.
Highlights
O RTHOGONAL frequency-division multiplexing (OFDM) signaling has been widely accepted due to its significant advantages over conventional single-carrier systems such as high bandwidth efficiency and robustness against frequency-selective fading channels with lowcomplexity receiver structure based on cyclic prefix (CP)
The CP length is chosen to be equal to the delay spread such that the inter-symbol interference (ISI) is negligible, and the channel state information (CSI) H is assumed to be available at the receiver
We have analyzed the performance of clipping and filtering (CAF) on OFDM signals with emphasis on the TD and FD iterative clipping compensation techniques applied at the receiver
Summary
O RTHOGONAL frequency-division multiplexing (OFDM) signaling has been widely accepted due to its significant advantages over conventional single-carrier systems such as high bandwidth efficiency and robustness against frequency-selective fading channels with lowcomplexity receiver structure based on cyclic prefix (CP). Several low-complexity iterative distortion recovery techniques have been proposed, and they are largely categorized into the two approaches: time-domain (TD) and frequency-domain (FD) compensation The former is represented by the decision-aided reconstruction (DAR) [11], whereas the latter is well known as the clipping noise cancellation (CNC) [12]. A new analytical model of OFDM systems with CAF suitable for analyzing time-domain distortion compensation approach, and theoretically derive a closed-form upper bound on its achievable signal-to-noise plus distortion ratio (SNDR). 2) A new timedomain analytical model for the distortion associated with CAF is introduced, based on which the upper bound of SNDR for the receiver with TD signal reconstruction is developed. The same rule applies to their vector representations given in the bold-face letters
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