Zero-forcing frequency domain equalization for DMT systems with insufficient guard interval

A generalized discrete multitone (GDMT) scheme that not only uses the guard interval but also redundancy in the frequency domain for equalization has been introduced recently [1, 2, 3]. Instead of assigning all redundancy in the time domain it allows to take advantage of unused subcarriers to remove ISI and ICI. In this paper, we calculate the signal-to-noise ratio for each subcarrier for the zero-forcing equalizer proposed in [3]. From there, we derive a new adaptive loading algorithm that optimally chooses the length of the guard interval and the position of unused subcarriers. The cost function applied for the adaptive loading algorithm is the achievable data rate at a fixed error probability.