Environmental and Motion Effects on Orthogonal Frequency Division Multiplexed On-Off Keying

Orthogonal frequency division multiplexing with on‐off keying (OFDM‐OOK) offers a means to near BPSK signaling rates with the simplicity of non‐coherent processing. At high frequencies source receiver acceleration induces time varying signal dilations that adversely effect both frequency alignment and multicarrier orthogonality. Dilation process estimation is coupled with a decision directed frequency domain channel magnitude response estimator for non‐coherent equalization of OFDM‐OOK. Joint co‐channel estimation is presented for near optimal decisions under loss of orthogonality due to Doppler spreading. Data from a moving source experiment at ranges from .8 km to 2.0 km, conducted in the shallow water off the coast of Elba Italy were used to test the feasibility of OFDM‐OOK at 18kHz center frequency with 4 kHz bandwidth. The effects of source receiver relative motion, frequency selectivity, and Doppler spreading on bit error rates were assessed. Mollification of frequency selective fading by diversity ...