Measurement study of scheduler-based attacks in 3G wireless networks

Though high-speed (3G) wide-area wireless networks have been rapidly proliferating, little is known about the robustness and security properties of these networks. In this paper, we make initial steps towards understanding these properties by studying Proportional Fair (PF), the scheduling algorithm used on the downlinks of these networks. We find that the fairness-ensuring mechanism of PF can be easily corrupted by a malicious user to monopolize the wireless channel thereby starving other users. Using extensive experiments on commercial and laboratory-based CDMA networks, we demonstrate this vulnerability and quantify the resulting performance impact. We find that delay jitter can be increased by up to I second and TCP throughput can be reduced by as much as 25 - 30% by a single malicious user. Based on our results, we argue for the need to use a more robust scheduling algorithm and outline one such algorithm.