Predicting link level performance for enhanced uplink

The enhanced uplink feature is currently being standardized in release-6 of the 3GPP Universal Mobile Telecommunications System (UMTS). The goal of enhanced uplink is to increase the sector and user throughput on the uplink relative to release-5 UMTS through the use of advanced techniques such as adaptive modulation and coding, node-B controlled scheduling, and hybrid-ARQ. In order to effectively analyze system capacity of enhanced uplink, a suitable link error prediction methodology is needed. In this paper, two methods for predicting uplink performance, namely, short-term method and equivalent SNR method based on convex metric (ECM) are presented. The ECM method is simpler to implement since it requires only AWGN curves, whereas the short-term method requires curves for all radio configurations. Performance of these two methods is compared under various channel conditions and with hybrid ARQ enabled. In addition, the effect of chip and frame timing offset on E-DCH link prediction using ECM and the short-term approach is presented in this paper. Our results show that the ECM prediction method provides results that are very close to those obtained from actual simulations. Hence, the ECM method can be used to accurately model link level performance for the 3GPP enhanced uplink.