Evaluation of modulation techniques for broadband access over twisted pair.

Abstract

This thesis is a study of modulation techniques which could be used to provide Asymmetric Digital Subscriber Line (ADSL) and Very-high-speed Digital Subscriber Line (VDSL) services over Unshielded Twisted Pair (UTP). Three all-digital modulations are considered: Carrierless AM-PM (CAP), FFT Discrete Multitone (FFT-DMT) and Cosine Modulated Filter Bank Discrete Multitone (CMFB-DMT). The relative merits of the three modulations are examined at two data rates, 6 Mbps and 26 Mbps, which are representative of downstream ADSL and VDSL rates, respectively. Block diagrams and mathematical descriptions are provided for all three modulations. A discussion of modeling the UTP channel and a number of impairments, namely AWGN, self-FEXT, NEXT, narrow-band interference and impulse noise, is also included. Time-domain BER simulation strategies are outlined for all three modulations. The simulated BER performance of 16-CAP and the two multicarrier modulations in the presence of AWGN is presented. The simulated BER performance in the presence of AWGN of 16-CAP VDSL with emission masking is included. The spectral isolation properties of the CMFB and FFT filters are examined briefly. The computational complexity in terms of real operations per bit is considered for 16-CAP, CMFB-DMT and FFT-DMT at ADSL and VDSL data rates. (Abstract shortened by UMI.)