An improved Fischer-Huber loading algorithm for reliable applications on access power line communications

The original Fischer-Huber loading algorithm attempts to minimize the probability of bit error by maximizing the signal to noise ratio. Bits are allocated to achieve the same error probability in each of the used subcarriers. However, in channels with a high difference in attenuation like access Power Line Communications (PLC) channels, this could result in overallocation for parts of the subcarriers, which is unreasonable in practice but is neglected during the bit allocation in the algorithm. Furthermore, after defining the upper boundary of constellation, the bit allocation is changed and then the method of flat power allocation generates a bad error probability. In this paper, we present an improved Fischer-Huber loading algorithm for access PLC channels with high attenuation variability. By adding constellation limitations and adjusting the power allocation policy, the improved algorithm appears more flexible. Simulation results show the improved performance.