Robust and high-bit rate communications over PLC channels: a bit-loading multi-carrier spread-spectrum solution

In this paper, we present a finite-granularity loading algorithm for multicarrier spread-spectrum modulation systems. The proposed scheme attempts to give a robust solution to the power line communication challenging task. Throughout the paper, the particular case of an adapted version of multi-carrier code-division-multiple-access (MC-CDMA) is considered, which is currently called spread-spectrum multicarrier multiple-access (SS-MC-MA). The presented algorithm assigns subcarriers, spreading codes, bits and energy per code to each user of the network in order to maximize the minimum data rate at a target symbol error rate (SER) and for a given power spectral density (PSD). Simulation results of the new scheme are presented for different measured PLC channels with impulsive noise and are compared with those of the classical discrete multitone modulation (DMT) approach. Then, it is shown that the proposed scheme offers higher throughput than DMT or less sensitiveness to impulse noise effects.