Design of a Gigabit DSL modem using super orthogonal complete complementary codes

Abstract

This paper describes the preliminary design and simulation towards a gigabit digital subscriber line modem that provides multi-user interference-free communication in a far-end crosstalk dominated environment by incorporating super orthogonal complete complementary spreading into the existing xDSL modem architecture. This is in contrast to existing vectoring and dynamic spectral management techniques that use joint processing and pre-processing of each user's signal to mitigate far-end crosstalk. A novel code allocation algorithm is introduced to provide all users with equal data rate ratios, even with bad line profiles and high-required data rates. Preliminary simulation results show that 1 Gbps aggregate throughput can be obtained for the system over a single pair of 0.5 mm copper wire over a distance from 180 to 150 m, depending on whether ADSL2+ or VDSL2 Profile 30a service bands are avoided, if present.