Performance Evaluation of Fast Link Adaptation Algorithm for Ofdm Systems

This paper investigate link quality metrics (LQMs) based on effective signal-to-interference-and-noise ratio, and mutualinformation (MI) for the purpose of fast link adaptation in communication systems employing orthogonal frequency division multiplexing and multiple-input multiple output (MIMO) antenna technology. From these LQMs the packeterror-rate (PER) can be estimated and exploited to select the modulation and coding scheme (MCS) among various MCSs that achieves the maximum throughput for the current channel state under a specified target PER objective. We propose a novel MI-based LQM and compare the PER estimation accuracy obtained with this LQM with that resulting from using other LQMs by means of system level simulations. Search methods for the most suitable MCS among various MCS for a given channel state are presented. The investigated LQMs are applied to the IEEE 802.11n standard with a 2x2 MIMO configuration and practical channel estimation. The proposed MI-based LQM yields the highest PER estimation accuracy for the current noise variance. Keywords—Adaptive modulation and coding, link adaptation, link quality metrics, channel state information, fading, feedback delay, OFDM, MIMO, PER estimation.