Study on Adaptive Modulation Used in Fading Channels

Abstract:

Most of traditional modulation and coding techniques do not adapt to fading or nonlinear conditions. These non-adaptive methods require a fix-link margin to maintain acceptable performance when the channel quality is poor. Thus, these systems are effectively designed for the worst-case channel conditions, resulting in insufficient utilization of the full channel capacity. Adapting to signal fading allows the channel to be used more efficiently since the power rate can be adjusted to take advantage of favorable channel conditions. In this paper, we present a simplified mathematical model to calculate the probability of SER for any given constellation of M-QAM. This model plays an important role in designing spectrally efficient adaptive modulation over nonlinear mobile channels. Instantaneous spectral efficiency and its histogram distribution are found for linear and nonlinear channel cases.

• Periodical: Applied Mechanics and Materials (Volumes 303-306)
• Pages: 2068-2071
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.303-306.2068
• Online since: February 2013
• Authors: Xin Wang, Wei Gao, Zong Xi Song
• Keywords: Adaptive Modulation, Fading Channels, Predistortion Techniques

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DOI: 10.1109/jsac.1984.1146101