A dual-path TEQ structure for DMT-ADSL systems

Discrete Multitone (DMT) modulation is the industry standard for Asymmetrical Digital Subscriber Loop (ADSL) modems. DMT modulation allows for simplified equalization when the effective duration of the channel memory is shorter than the predefined length of the cyclic prefix (CP). A single time-domain equalizer (TEQ) is typically used to truncate the channel memory such that the data rate loss due to the use of the CP is reduced. Because the single TEQ is optimized over all sub channels, it is difficult to find an ideal solution in which the number of bits supported on each sub channel is optimized. This paper proposes a dual-path TEQ, which adds a second TEQ that is biased to selected sub channels to increase transmission throughput. The implementation complexity is lower than other band-partition equalization methods such as per tone equalization.