Abstract :
Single-carrier modulation such as quadrature amplitude modulation (QAM) or carrierless amplitude modulation-phase modulation (CAP), and DMT are alternative techniques for providing digital communication in a variety of applications, in particular ADSL for communication over the telephone company subscriber lines. Although theory predicts comparable performance under ideal implementations, a definitive comparison of performance over a wide range of conditions will require more experience from field trials. Similarly, accurate comparison of implementation costs must await the greater availability of commercial-grade devices. However, enough is now known about these modulation schemes to compare their inherent similarities and differences in performance and cost. Overall, a present view of single-carrier and multitone modulation indicates comparable performance with some differences depending on the type of degradation. Costs should also be approximately equal, with multitone having some advantage in digital processing, but requiring greater cost in analog circuitry
Keywords :
digital communication; digital subscriber lines; phase modulation; quadrature amplitude modulation; ADSL applications; CAP; DMT; QAM; analog circuitry; carrierless amplitude modulation-phase modulation; commercial-grade devices; degradation; digital communication; digital processing; field trials; implementation cost; implementation costs; multitone digital modulation; performance; quadrature amplitude modulation; single-carrier modulation; subscriber lines; telephone company; Amplitude modulation; Availability; Circuits; Costs; Degradation; Digital communication; Digital modulation; OFDM modulation; Quadrature amplitude modulation; Telephony;