Performance of single-tone and two-tone frequency-shift keying for ultrawideband

By using impulsive frequency-shift keying (FSK) with vanishingly small duty cycle, capacity can be achieved in the limit of infinite bandwidth in wideband systems that decorrelate in time and frequency. With limits on bandwidth and peak power, impulsive FSK schemes with small duty cycle can still achieve rates of the order of capacity in ultrawideband systems. We compare performance of a single tone and two-tone FSK schemes. Our results indicate that two-tone FSK can be applicable at lower bandwidth with almost no detriment in the error exponent.