Performance measurement over 3G and 3.5G wireless networks

Abstract

In this work, we have conducted extensive end-to-end measurements to capture the characteristics of variability of wireless link, to analyze its impact on TCP behavior, and to evaluate QoS of VoIP applications over operational 3G and 3.5G wireless network such as CDMA-1xEVDO, HSDPA, and WiBro. Our measurement include UDP/TCP traffic traces and VoIP traffic simulated by D-ITG, as well as several physical layer information of a base-station to which a mobile device is connected. In order to capture the baseline performance of the 3G and 3.5G wireless network we measure and analyze the characteristics of throughput, delay, and loss under stationary and mobile scenarios. In addition, we quantify the degree of variability and demonstrate it graphically using second-order difference plot. Then to investigate TCP behavior on variable wireless link state which becomes more significant in mobile environment, we further analyze TCP performance metrics such as ACK compression and serveral types of retransmission. Finally, we evaluate QoS of VoIP applications using the E??Model of ITU-T G.107. Our measurements show that the achievable maximum throughput and variability in uplink and downlink of each wireless network. We note that even in stationary environment, there is an inefficiency of the interplay between TCP congestion algorithm and wireless link mechanisms, which results in performance degradation. VoIP quality is better than or at least as good as toll quality despite user mobility exceeding the protected limit of each wireless network mobility support. Using RAS and sector identification information, we show that the handoff is correlated with throughput and quality degradation.