Implementation of ASK-OFDM Exploiting the Property of Symmetry

摘要

A method to implement OFDM using amplitude shift keying (ASK) for subcarrier modulation is presented in this paper. Because ASK is used, the signal of each symbol in the time domain is conjugate-symmetric. This property is exploited such that only half of the numbers of each symbol sequence are transmitted. The generated baseband signal can be a complex or a real signal. ASK-OFDM has similar bandwidth efficiency and the same error rate performance in an AWGN channel as in a QAM-OFDM. Compared with QAM-OFDM, ASK-OFDM provides a method of distributing signal energy more evenly in the frequency band. In other words, ASK-OFDM signal possesses better frequency diversity than QAM-OFDM signal.