Initialization and bitloading of discrete multi-tone transceivers for channels with unknown impulse response length

In this paper, we consider a DMT (discrete multi-tone modulation) transceiver with a guard interval of insufficient length. We describe an algorithm that estimates the channel impulse response correctly, independently of its length, while keeping the guard interval at the preset length. The training sequence is designed such that inter-symbol and inter-carrier interference cancel. We then show that calculating the one-tap equalizer per subcarrier, as the inverse of the channel frequency response at the subcarrier frequency, is not optimal in the presence of interference. We also propose an improved bitloading algorithm, based on measured signal-to-noise-and-interference ratios.