Calibration Issues of PHY Layer Abstractions for Wireless Broadband Systems

Today link-to-system (L2S) interfaces are more and more used in order to speed up complete system-level simulations. In this paper a simple extension to generic incremental redundancy (IR) hybrid automatic repeat request (HARQ) strategies is presented for two well-known L2S interfaces: the exponential effective SNR metric (EESM) and the mutual information effective SNR metric (MIESM). Then we focus on the problem of the L2S interface tuning, which is necessary to achieve the highest accuracy of the prediction models. The standard calibration procedure is compared with a new method, based on the average (over channel and noise) physical (PHY) layer performance. The latter, called average calibration procedure, is less time consuming than the standard procedure. Moreover, we show by simulation that the optimal calibration factors, calculated with the two methods, converge to close values thus obtaining equivalent prediction accuracy for the same L2S interface.