Modified EESM Based Link Adaptation Algorithm for Multimedia Transmission in Multicarrier Systems

TL;DR

This paper proposes a modified EESM-based link adaptation algorithm for multimedia OFDM transmission, accounting for unequal constellations within subcarrier blocks and deriving theoretical BER performance under correlated fading.

Contribution

It introduces a novel link adaptation algorithm using EESM for multimedia OFDM systems with unequal constellations and provides a mathematical model for correlated fading channels.

Findings

BER performance improves with the proposed algorithm.

Theoretical BER derived for correlated bivariate Gaussian channels.

Performance varies with correlation and fading parameters.

Abstract

The previous link adaptation algorithms on ofdm based systems use equal modulation order for all sub carrier index within a block. For multimedia transmission using ofdm as the modulation technique, unequal constellation is used within one ofdm subcarrier block, a set of subcarriers for audio and another set for video transmissions. A generic model has been shown for such a transmission and link adaptation algorithm has been proposed using EESM (Effective Exponential SNR mapping) method as basic method. Mathematical model has been derived for the channel based on bivariate Gaussian distribution in which the amplitude varies two dimensionally in the same envelope. From the Moment generating function of bivariate distribution, Probability of error has been theoretically derived. Results have been shown for BER performance of an ofdm system using unequal constellation. BER performances have been shown for different values of correlation parameter and fading figure.