Cancellation Symbol Insertion Technique for Sidelobe Suppression in OFDM Pilot Waveform

摘要

In the paper, the cancellation symbol insertion (CSI) technique is adopted to suppress the sidelobe power of the OFDM pilot waveform while maintaining the channel estimation (CE) optimality on the quasi-static multipath channel. Different from the conventional CSI technique where the cancellation symbols (CSs) are designed to suppress the sidelobe power of composite OFDM waveforms conveying data and pilot symbols, the proposed CSs depend on pilot symbols only and can be known to the receiver. Hence, the CSs can be used to assist channel estimation when they are conveyed on guard subcarriers or reduce the cancellation symbol power without causing interference to data demodulation when they are superimposed on data subcarriers. The composite OFDM waveforms conveying spectrally precoded data symbols, optimum pilot symbols, and the proposed CSs are shown to exhibit highly compact spectrums, while providing enhanced CE and requiring reduced cancellation symbol power. Index Terms: Orthogonal frequency division multiplexing, cancellation symbol, sidelobe suppression, pilot symbol, channel estimation.