Multicarrier bit-loading in presence of biased Gaussian noise sources

Abstract

Certain types of non-Gaussian noise sources in multicarrier communication systems behave effectively as modulating signals that control the first moment of the background Gaussian noise. The composite noise, which is the aggregate of the Gaussian and non-Gaussian noise, has a probability density function that is conditionally Gaussian with non-zero average, hence referred to as biased-Gaussian. Impulsive interferers and timing-phase error are examples of such non-Gaussian noise sources. The BER-equivalent power of a composite noise source is defined as the power of a pure Gaussian noise source that yields the same bit-error rate (BER). The BER-equivalent noise for a biased-Gaussian noise is simply the amplified version of the underlying Gaussian noise source. The amplification factor is derived from the characteristics of the non-Gaussian noise source. Any bit-loading algorithm designed for Gaussian noise sources is also applicable to biased-Gaussian noise sources provided that the BER-equivalent SNR is used in place of the measured SNR.