Measured TCP Performance in CDMA 1x EV-DO Network

This paper investigates the long-lived TCP bulk throughput over the CDMA 1x EV-DO service that provides high-speed “always on” Internet connectivity in a wide-area mobile environment. Although the peak rates of downlink/uplink are specified as 2.4 Mbps/153 Kbps, the user-experienced application-layer throughput has not been much reported and analyzed. In our experiment, it was shown that average TCP throughputs over downlink/uplink are 572.5/94.7Kbps and the average packet loss rates of 1x EV-DO downlink/uplink are 0.2/4.7%. The average end-to-end round-trip delay was 417.4ms with the variance of 14,995ms. Although the packet loss rate is low, bursty packet losses frequently occur because of packet corruption with TCP checksum failures, which result in TCP performance degradation by the retransmission timeout. Our study showed that this TCP checksum errors are related with the TCP/IP header compression algorithm at link layer protocols such as PPP. Our measurement-based analysis of TCP performance could be used for the correct model of the 3G wireless link characteristic and for the real-world simulation of TCP behavior over the 3G wireless network.