Postfix Design for Pseudo Random Postfix OFDM Modulators

This contribution1 details the derivation of suitable discrete postfix sequences for the recently proposed pseudorandom-postfix OFDM (PRP-OFDM) modulation scheme; these sequences are used in order to estimate and track the propagation channel impulse response (CIR) and have to meet the following requirements: Minimum out-of-band radiation for transmission mask requirements, spectral in-band flatness for CIR estimates with homogenous mean-square-error (MSE) over all useful carriers and low Peak-to-Average-Power-Ratio (PAPR). In order to derive such sequences, a steepest-descent based iterative optimization approach is proposed starting with the KaiserWindow as initial sequence which is optimum except for the PAPR criterion. The proposed algorithm is applied to the 5GHz IEEE802.11a WLAN context and the final postfix sequence is evaluated by the upper criteria.

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