Spectral optimization of discrete multitone system on twisted wire copper pairs

This paper describes a spectral optimization algorithm that shapes the spectrum of the transmit signal in order to maintain spectrum compatibility between a discrete multitone (DMT)-based transmission system and existing services on twisted wire copper pairs. Performance results are presented for a specific application of DMT to transport asymmetric digital subscriber lines (ADSL) payloads at data rates of over 6 Mb/s in the downstream direction. We consider spectral compatibility between ADSL, the T1 repeater system, high bit-rate DSL (HDSL), and integrated services digital networks (ISDN) basic rate access (BRA) systems. Lagrange multipliers are used to solve the constrained optimization problem.