System Level Evaluation of Interference in Vehicular Mobile Broadband Networks

This paper presents results from a novel OFDMA multi-cell mobile broadband system-level simulator. The tool is used to statistically characterize uplink and downlink inter-cell interference. Fully loaded interference studies cannot be performed on real-world networks until they have been fully deployed. As such, interference analysis and management must be accurately performed pre- deployment using detailed network simulators. This paper discusses our simulator architecture and the steps necessary to reduce computational complexity inherent in such simulations. The paper then demonstrates the impact of inter-cell interference in OFDMA networks. The results demonstrate that it is the frame-to-frame fluctuations in interference, and not the received signal level, that dominate inaccuracy in the Channel Quality Index (CQI). CQI errors lead to the wrong MCS mode being chosen by the AMC algorithm and this leads to throughput reduction. Results show that this problem is exacerbated by high vehicular speeds and the absence of interference randomization. Compared to ideal MCS selection, throughput reductions of up to 45% are reported.