Bit rate optimized time-domain equalizers for DMT systems

Abstract

The discrete multitone (DMT) transceivers have enjoyed great success in high speed data transmission. It is known that when the cyclic prefix is no shorter than the channel impulse response (CIR), the DMT system is ISI free. For channels with very long CIR such as DSL loops, a time-domain equalizer (TEQ) is typically added at the receiver to shorten the effective impulse response. This paper proposes a filterbank approach to the design of TEQ for maximizing the bit rate. Moreover we introduce the structure of a DMT system with multiple TEQs. The optimal solution for multiple TEQs is given in closed form and it can serve as a theoretical upper bound for all other TEQs. From the multiple TEQ structure, we propose a DMT system with a pair of complex conjugating TEQs. Simulation examples are given to verify the merit of the proposed TEQ.