Energy-minimizing bit allocation for powerline OFDM with multiple delay constraints

Abstract

We propose a bit-allocation scheme for powerline orthogonal frequency-division multiplexing (OFDM) that minimizes total transmit energy subject to total-bit and delay constraints. Multiple delay requirements stem from different sets of data that a transmitter must time-multiplex and transmit to a receiver. The proposed bit allocation takes into account the channel power-to-noise density ratio of subchannels as well as statistic of narrowband interference and impulsive noise that is pervasive in powerline communication (PLC) channels. The proposed scheme is optimal with 1 or 2 sets of data, and is suboptimal with more than 2 sets of data. However, numerical examples show that the proposed scheme performs close to the optimum. Also, it is less computationally complex than the optimal scheme especially when minimizing total energy over large number of data sets. We also compare the proposed scheme with some existing schemes and find that our scheme requires less total transmit energy when the number of delay constraints is large.

Modelling impulsive noise in indoor powerline communication systems

“…These noise sequences are generally non-Gaussian and are classified into three groups, namely i) impulsive noise, ii) narrowband noise and iii) background noise [3]. Impulsive noise in PLC systems is the most common cause of communication errors compared to other types of noise due to its high amplitudes which can exceed 50 dBs [4,5].…”