In this study we present network-wide measurements of Round-Trip-Time (RTT) from an operational 3G network, separately for
GPRS/EDGE and UMTS/HSxPA sections. The RTTs values are estimated from passive monitoring based on the timestamps of TCP handshaking
packets. Compared to a previous study in 2004, the measured RTT values have decreased considerably. We show that the network-wide
RTT percentiles in UMTS/HSxPA are very stable in time and largely independent from the network load. Additionally, we present
separate RTT statistics for handsets and laptops, finding that they are very similar in UMTS/HSxPA. During the study we identified
a problem with the RTT measurement methodology — mostly affecting GPRS/EDGE data — due to early retransmission of SYNACK packets
by some popular servers.