Capacity and error probability in single-tone and multitone multiple access over an impulsive channel

Single-tone and multitone are two modulation methods which can combine mult iple digital users over a single channel, and decode them independently, co rresponding to time-division and frequency-division multiple access, respec tively. When the channel noise is impulsive, its distribution at the receiv er decision point, and therefore its effect on the users, depends strongly on the type of modulation. We quantify this effect using information theore tic measures: capacity and error-exponent, where the latter is represented by its cut-off rate parameter For low to moderate impulse power, the cut-of f rate associated with multitone is greater than the cut-off rate associate d with single-tone-in contrast to the relation between the corresponding Sh annon capacities. This leads to anomalous behavior of the error-versus-info rmation-rate performance. We show that this behavior relates to the tendenc y toward Gaussianity of the noise after multitone demodulation. We also pro vide specific evaluation of this phenomena for advanced data transmission o ver the Cable TV (hybrid fiber coax) channel.