These trace files represent the time-varying capacity of U.S. cellular networks as experienced by a mobile user. They were recorded using the "Saturator" tool described in the research paper: K. Winstein, A. Sivaraman, and H. Balakrishnan, "Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks", USENIX NSDI 2013, https://www.usenix.org/conference/nsdi13/technical-sessions/presentation/winstein Each line gives a timestamp in milliseconds (from the beginning of the trace) and represents an opportunity for one 1500-byte packet to be drained from the bottleneck queue and cross the link. If more than one MTU-sized packet can be transmitted in a particular millisecond, the same timestamp is repeated on multiple lines. A fixed-rate link may also be represented a trace file. For example, a link that can pass one MTU-sized packet per millisecond (12 Mbps) can be represented by a file that contains just "1". By default, mm-link will repeat the trace file when it reaches the end, so this trace would represent one packet per millisecond.