NARROW-BAND PREAMBLE FOR ORTHOGONAL FREQUENCY-DIVISION MULTIPLEXING SYSTEM

摘要

A method of signal generation includes selecting a subset of contiguous OFDM symbols from a set of contiguous OFDM symbols, selecting a subset of contiguous subcarriers from a set of subcarriers, and generating a preamble that occupies the subset of contiguous subcarriers in the subset of contiguous OFDM symbols. The preamble includes portions in respective OFDM symbols of the subset of contiguous OFDM symbols. In the time domain each preamble portion corresponds to a repeating sequence of samples when subcarriers outside of the subset of contiguous subcarriers are filtered out. Generating the preamble may include flipping the sign of one or more occurrences of the repeating sequence for a final preamble portion and may include placing modulation symbols on regularly spaced subcarriers in the subset of contiguous subcarriers and phase-shifting the modulation symbols for a respective preamble portion with respect to a previous preamble portion.